# Good fish food source for potassium?



## ObiQuiet (Oct 9, 2009)

Hi,

I'm seeing a potassium deficiency (yellowing and holes in older leaves) in a tank that's been up since October. This coincides with the expected overall slow-down in growth. The city's water quality report shows no potassium in the tap water.

From Ms. Walstad's book, I understand that fish food in general should supply enough water-column potassium -- so I've doubled the feedings to see what happens.

But, I have not been able to determine whether the Tetra-brand flake food I'm using has any/much potassium. Is there a food good choice that does have potassium, suitable for the standard tetra/danio species?

(I can certainly add potassium as a fertilizer, but would prefer using the food chain.)

Thanks,
-ObiQuiet


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## Esteroali (Oct 1, 2007)

I have often wondered this same thing. I have a tank at work with RCS and 1 guppy. It does marvelous and the only thing I feed is Hakari (sp) micro pellets. Is it the food? I never fertilize this tank and the substrate is Eco-complete with some stray soil. Is it the food?


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## edwardn (Nov 8, 2008)

How about bananas?

The only problem is to teach fish to peel them...


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## Philosophos (Mar 1, 2009)

Spirulina-based flake, but the rising price of spirulina means most commercial "spirulina flake" is pretty watered down. You could try making your own. Gut loading live food with spirulina powder may work as well (daphnia perhaps?). The powder is about 15-16g/kg K+, which is maybe a little better than average.

Personally I'd just go with KNO3 and KH2PO4, maybe KCl if PO4 and NO3 seem a little on the high side. K2SO4 _should_ be fine if your substrate isn't hypoxic, but Diana seemed to think it would be a problem. I wouldn't mind hearing a little more on her reasoning with that one.


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## f1ea (Jul 7, 2009)

Philosophos said:


> Spirulina-based flake, but the rising price of spirulina means most commercial "spirulina flake" is pretty watered down. You could try making your own. Gut loading live food with spirulina powder may work as well (daphnia perhaps?). The powder is about 15-16g/kg K+, which is maybe a little better than average.
> 
> Personally I'd just go with KNO3 and KH2PO4, maybe KCl if PO4 and NO3 seem a little on the high side. K2SO4 _should_ be fine if your substrate isn't hypoxic, but Diana seemed to think it would be a problem. I wouldn't mind hearing a little more on her reasoning with that one.


Wow! good. That's an interesting take on nutrition via live-food.

I have read from Walstad that often K is the "difficult" nutrient in non-dosed or NPT tanks... I use some Tetra color pellets (which contains spirulina) and dose a little KNO3. So far I only see slight K deficiency in one type of Echinodorus (ie 1 yellowing old leaf per 5 in the plant or so). I just trim it.


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## Diana K (Dec 20, 2007)

I also found that fish food did not supply enough potassium, and that was the first thing I started dosing, then iron. 
I mostly had gravel substrate back then, so the substrate was no help. 
I have since switched over to a substrate with a much higher cationic exchange capacity, so as I was dosing, the substrate was sequestering a certain amount of the minerals and fertilizers, including, I assume, potassium.

I use K2SO4 as a potassium source. For me it works, no problem with sulfer compounds. 
I know there are other potassium sources that do no add sulfer to the tank.

I feed a lot of the foods from www.AlmostNaturalTropicalFishFood.com


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## Philosophos (Mar 1, 2009)

Gut loading live food is wonderful for spawning/coloring up your fish. Blackworms fed on spirulina and freeze-dried cyclops give a great load of carotenoids.

You know thinking of it, it'd probably work to just nutrient load the substrate with KNO3 at setup time. K+ is definitely the biggest limiting factor if you aren't adding it some other way. ADA is pretty much doing just that with their "power sand" which is understandable given the lean column/dosing.


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## ObiQuiet (Oct 9, 2009)

Thank you for the replies, everyone!

From what I can tell, each of the K additives have a detrimental component (sulphur, chloride, etc) that would build up over time. 

re: substrate -- I read that plants take potassium more readily from the water than the substrate, though they can do either.

re: trimming the yellow leaves -- if I understand, then the holes and yellowing are due to the plant actively migrating the K from old growth to new growth. Would trimming the old growth too early reduce the available K?

re: spirulina -- sounds good! I looked more in the book, and found a mention of feeding bits of boiled eggs to the fish -- might eggs may have higher levels of K than spirulina?

What do you think of the egg idea?

Very informative, thank you!


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## Philosophos (Mar 1, 2009)

Inorganic nitrate is obscenely hard to OD; something like 100+ppm. Chloride (not chlorine) is even less toxic; you can go up past 200ppm. I'm not so sure about PO4, but I've seen safe dosing in the 20ppm range. Most of these fertilizers people fear are things that we have consumed for hundreds of years or more without harm. I think many forget this, and have the concept of a scientifically named compound being some kind of horribly toxic chemical.

20ppm of NO3 means enough related waste to harm sensitive fish, meanwhile 20ppm of inorganic and many of us have discus or apistos spawning. Some have gone to twice that without any indication of harm. If you're already putting in NPK using organic waste through fish food, why not a low dose of something less toxic?

The only argument I see against it is trying to make a natural tank for the sake of making a natural tank. Considering what your average fish food contains (monsanto soy, marine fish meal), I'd consider the result of manure or urine and wood ashes (classic KNO3 method) little farther from accurate.

The eggs are going to be mostly fat and protein. I've found egg yolk fouls the water at an incredible rate.

If you have yellowing then it's probably more than K+. Nitrogen would be the #1 suspect, iron a distant second.


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## goldier (Feb 13, 2010)

Egg yolk contains fat, sulfur and many other elements, including small amount of K, while the egg white is mostly protein. The sulfur in egg yolk gives rotten egg odor (from H2S). 

Acidic water (low pH), where there are more H+ ions, would tend to accelerate H2S formation when there are sulfur precipitation in the substrate, besides the bacteria action, than in basic water (high pH). Solubility is pH dependent. From my recollection, a pH 7 would have about 50% H2S dissolved, while at lower pH at around 5-6, nearly 100% H2S dissolved in the water.

People with well water usually have problem with H2S. Unless the well water is treated to remove sulfur, it’s better to avoid adding sulfur sources into the water.


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## ObiQuiet (Oct 9, 2009)

Philosophos and Goldier,

I'm grateful for your detailed, reasoned, and quantified answers -- they give me much more info than the one-liners I found by searching. 

For me this is in good part a science project, and computing ppm and learning how the chemistry works contributes to making it interesting.

Based on what you've said, I'll be adding either KCL or KNO3 to start, and see how that goes.


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## mommyeireanne (Oct 24, 2007)

I dose with "No Salt" from the grocer. It's potassium chloride, so I dissolve it in some water and then add dechlorinator, when I top off the tank. Very easy. Diana Walstad had a post here about dosing it. I just use 1/8 to 1/4 teaspoon whenever I see the plants showing signs of deficiency.


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## f1ea (Jul 7, 2009)

Philosophos said:


> If you have yellowing then it's probably more than K+. Nitrogen would be the #1 suspect, iron a distant second.


Very good observation. 
By the way, the case I mentioned, I am getting a single old leaf (ussually the oldest) getting lots of brown spots/little holes and then slowly browning and turning yellow with bigger holes. I THINK it is a K defficiency, but I am not really paying too much attention to it because it happens only in one plant sp. (E. Cordifolius) and in one leaf out of each 5-6...

Another thing (in the case of Obiquiet) is that it can be little CO2 as well. Specially since you probably have a rich substrate and no CO2 injection (ie posting in El Natural forum). So, if I were you i'd check/make sure Co2 is enough (or lights not too high)... then dose KNO3 (that should help either N or K deficiency) or simply increase feeding and see what happens.


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## Philosophos (Mar 1, 2009)

Getting CO2 low in the tank isn't so much a challenge in an NPT. It's partial pressure keeping the CO2 down, and a lot of the organic carbon is being produced right at the substrate level.

Old growth yellowing with brown little holes is nothing less than multiple deficiencies. When I see brown around the edges of holes, I tend to think Mg deficiency though it's not always the case. Either way, it's always seemed to me that electrolyte deficiencies show fast in the big, broad leafed SAM's; they get holes long before anything else does. Odds are if your tap doesn't have Mg in it, then you'll be a bit more prone to deficiency. If the source for your substrate doesn't have much Mg, then it's definitely an issue.


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## f1ea (Jul 7, 2009)

Philosophos said:


> Getting CO2 low in the tank isn't so much a challenge in an NPT. It's partial pressure keeping the CO2 down, and a lot of the organic carbon is being produced right at the substrate level.
> 
> Old growth yellowing with brown little holes is nothing less than multiple deficiencies. When I see brown around the edges of holes, I tend to think Mg deficiency though it's not always the case. Either way, it's always seemed to me that electrolyte deficiencies show fast in the big, broad leafed SAM's; they get holes long before anything else does. Odds are if your tap doesn't have Mg in it, then you'll be a bit more prone to deficiency. If the source for your substrate doesn't have much Mg, then it's definitely an issue.


What do you mean by getting CO2 low in the tank isn't much of a challenge? 
Do you mean low as in... at substrate level, or low as in quantity (ppm)? Depending on the ammount/duration of light and the type of plants Obiquiet is growing he may have not enough CO2. Also, depending on what soil he initially used (or how much bioload) he may not have enough organics to produce CO2... and from there the deficiencies.

In my case, I have moderately hard water GH 12 dH and KH 7; no other plant shows this deficiency. But I do know my CO2 is not enough; I'm not using pressured, only DIY + excel.

Regards


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## ObiQuiet (Oct 9, 2009)

Yes, this is a Miracle-Gro soil substrate under Flourite with no added CO2. I can post the current KH reading, watts, etc. later today.


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## Philosophos (Mar 1, 2009)

f1ea said:


> What do you mean by getting CO2 low in the tank isn't much of a challenge?
> Do you mean low as in... at substrate level, or low as in quantity (ppm)? Depending on the ammount/duration of light and the type of plants Obiquiet is growing he may have not enough CO2. Also, depending on what soil he initially used (or how much bioload) he may not have enough organics to produce CO2... and from there the deficiencies.
> 
> In my case, I have moderately hard water GH 12 dH and KH 7; no other plant shows this deficiency. But I do know my CO2 is not enough; I'm not using pressured, only DIY + excel.
> ...


At the substrate level. In compressed/DIY systems the ppm's are higher so the CO2 gasses off faster. A lot of the time people end up with poor circulation lower in the tank, so they'll go on about their yellow drop checker... until they move it near the substrate and it turns blue. Lower light systems don't have this problem really; CO2 is pretty close to non-limiting without the addition. NPT's even less so.

Even with mineralized soil, a low light NPT should gain organics through plant waste. If the leaves are breaking down at the substrate, then there's ammonifying bacteria carrying out organic processes.

That being said, OBQ's report on wattage may turn something up.

f1ea, if you've got CO2 issues and you aren't able/don't want to do compressed yet, then there's any number of ways to reduce your lighting without buying a different fixture.


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## ObiQuiet (Oct 9, 2009)

Okay, here are the specs. 

Before I start that, though, just wanted to point out that I don't think I have a serious deficiency - at least not yet! The leaf holes and yellowing that have shown up so far are the first signs of deficiency in this, my first NPT. 

I did some reading, and learned that K was the likely culprit... if Mg and others go along with it, that's good to know. 

Happy for you to dig into the details so that I can learn in the process!

Tank:
37g tall (17" surface-to-substrate)
Substrate is miracle-gro top soil, capped with flourite
Elapsed time: 6 months
Moderate mulm around plant roots, maybe 40% covered
UV runs 2x2h per day, which is also the source of circulation
No surface agitation

Lighting:
4x13W=52W cool white T5 NO, ~3000k to 4500k
On for 4.5h, off for 4h, on for 4.5h, daily
No sunlight

Fish, etc:
6 Zebra Danio, 6 Cardinal Tetra, 2 Oto, 1 Cherry Barb, 2 Amanos, ~20 RCS, plus not-quite-too-many ramshorns

Plants:
Red Wendtii, pinholes, larger holes, yellowing older growth
Amazon Sword, growth slowed, pinholes and yellowing older growth
Marsilea Quadrifolia, a few stems turned yellow and got holes

Bacopa Monnieri doing great, no yellow, no holes
Vallisneria Spiralis doing great, no yellow, no holes

Duckweed, slowed way down in the last 2 months
Hornwort, slowed way down, nearly gone now

Ludwigia Repens, no yellowing, slow growth
Egeria Najas, no yellowing, slow growth

Java mosses - no change


Today's Measurements:
pH 7.5, (steady)
KH 89ppm, (down today from normal 107ppm)
GH 125 (steady)
0 Nitrate (never had a measurable level)
0 Ammonia (never had a measurable level)

Water:
Water changes have been limited, after the initial start -- topping off with tap water or RO water as the KH/GH indicated.
City water quality report:
39ppm Ca
21ppm Mg
22ppm Na
0ppm Fe
They don't list K, so I've asked if that's because there isn't any or if it's not tested for.

Let me know if I missed anything,

-ObiQuiet


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## Philosophos (Mar 1, 2009)

Goldier I completely missed the last part of your post so I'll reply now.

People with well water are getting H2S directly from the well quite possibly. If it's a matter of SO4, the question would still be, "why is my substrate reducing sulfates at a significant rate to begin with?"

Another important question might be why Diana is saying it's dangerous to add K2SO4 when the ratio of potassium to sulfur is actually a little over 1% higher in the food outlined on page 79. I imagine the same issue would continue down on the light to anyone else who claims fish food is safe, but K2SO4 is not, as a matter of sulfate reduction.

*EDIT* Looks like I posted about the same time as OBQ... I'll get typing and post some more.


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## Philosophos (Mar 1, 2009)

You're doing El Natural with all the makings for high tech, just need to get you some CO2 

I can't recall the book's position, but I'm pretty sure UV sterilizers are not in the spirit of El Natural. I'm not sure what Diana would say in regards to nuking so many little critters that the method is founded around either. I'd look into it more closely, maybe crunch some numbers with flow rates and potential bacteria doubling times to see what the long-term impact could be.

6 months is way to early for a substrate burnout, but your light is high enough that your plants may not be able to pull potassium from the substrate alone at a decent pace. The light you have on there is about when I start dropping hints that if you want a stable tank, compressed CO2 is the option. Think of T5's with their low restrike and fancy reflectors as being 1.5x the wpg. I may be wrong; those lights may have a very low PAR value as well. Ever considered turning one off, and running perhaps two 5 hour photo periods as an alternative?

I have no clue how you have anything that looks remotely like nitrogen deficiency with tap water like that and a nutrient loaded substrate. Mg is out of the question too.

Perhaps start with the light reduction and check to see if it's CO2. Yellowing isn't one of the primary symptoms, but I've had it happen severely on staurogyne. My foot may be in my mouth on this one; I wasn't expecting to see a lighting rig like that over a tank with such a small footprint.

Now for something I forgot in the last post. I find it interesting that sulfur in the substrate would be an issue because of H2S at 0.034ppm, but the substrate its self would already be providing ~1000-1800g/l of sulfur. I wonder just how much is reducing.


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## ObiQuiet (Oct 9, 2009)

Philosophos said:


> You're doing El Natural with all the makings for high tech, just need to get you some CO2


That's actually pretty funny... 



Philosophos said:


> I can't recall the book's position, but I'm pretty sure UV sterilizers are not in the spirit of El Natural.


There's a thread or two where she recommends them: http://www.aquaticplantcentral.com/...-filtration-soil-turbidity-uv-submariner.html

See also these: http://www.aquaticplantcentral.com/forumapc/el-natural/67410-balancing-uv-needs-floating-plants.html
www.aquaticplantcentral.com/forumapc/algae/68427-uv-sterilizers-2.html



Philosophos said:


> your plants may not be able to pull potassium from the substrate alone at a decent pace.


At the bottom of p. 104 the book says that plants prefer potassium uptake from the water. See also p. 81 where she says that K is readily taken up from fish waste. This is what led me to ask originally if there was a food that would supply K to make up for the apparent deficiency.



Philosophos said:


> The light you have on there is about when I start dropping hints that if you want a stable tank, compressed CO2 is the option. Think of T5's with their low restrike and fancy reflectors as being 1.5x the wpg. I may be wrong; those lights may have a very low PAR value as well. Ever considered turning one off, and running perhaps two 5 hour photo periods as an alternative? Perhaps start with the light reduction and check to see if it's CO2. Yellowing isn't one of the primary symptoms, but I've had it happen severely on staurogyne. My foot may be in my mouth on this one; I wasn't expecting to see a lighting rig like that over a tank with such a small footprint.


lol. Yes, I see what you mean. I can easily turn one off, and will try that. Don't over-rate my lights, though -- these have no fancy reflectors, in fact have no reflectors at all. They're just everyday GE Slimline under-cabinet lights, with normal-output bulbs. The total watts is my attempt to compensate for the tank depth and the lack of reflectors. I should have made that clear.



Philosophos said:


> I have no clue how you have anything that looks remotely like nitrogen deficiency with tap water like that and a nutrient loaded substrate. Mg is out of the question too.


To be fair, I now realize that I've thrown some challenges into my originally-simple question. Like using both RO and tap water -- which makes it impossible now to know how much Mg went in over the last 6 months... and the excess lights... and other things...

What I'm still curious about is table V-2 on p. 79 which seems to indicate that fish food is a sufficient supplier of all the elements we've been discussing, yet people still regularly add K (and others) to El Natural tanks. Not a big deal, but I thought I might be using the "wrong" food.

Cheers,
-ObiQuiet


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## Philosophos (Mar 1, 2009)

No reflectors at all? You probably don't need to turn down the lighting. Do you have a club in the area? Even a salt water one? You may be able to get your hands on a PAR meter to take a better look.

I didn't see the UV thing coming... that's a weird one given her cautious attitude about Excel's biocidal activity. There again, I don't know the details on the topic of microbiology remotely so well as her. It'd be a waste of my time to try to question it.

K+ and other electrolytes are definitely prime candidates for uptake everywhere; they'll passively diffuse into just about anything, and head through stoma like nothing.

I don't agree that her example fish food has enough K+ to buffer for all situations though. The numbers are internally integral, but they don't include the requirement fish have for potassium. More importantly, the numbers don't necessarily fit with the full range that SAM's can demand. Google "Elemental Compostion of Five Aquatic Submerged Aquatic Plants" and open the pdf; should be something by the journal of aquatic plant management. You'll see the upper K+ ranges I'm talking about. Even supposing 30mg/g dry weight of K+ is going to result in a 600mg/month demand. In a 50 gal tank we're talking about 3.2ppm of K+ in the column. I'm not sure plants even have an equilibrium that low, and feeding to pad that number isn't so hot. The resulting NH4 from waste is something like 18-21ppm dosed per month. The math there would be N = ~16g/mol, H = ~1g/mol, so NH4 would be 20g/mol, 20/16=1.2, multiply by 17.56 as established from 83ppm N * 40g per wk / 50 gal in liters. Maybe subtract 10-20% for hardscape and squishy bits. Double that quantity would be required to get enough padding for K+ through food.

Anyhow, it looks like KCl has been confirmed as a method in the past. Species limitations aside, Potassium is definitely the big issue of NPT's. It's really not that big of a problem. When tanks get enough light to demand compressed CO2, then you've got bigger headaches. Maybe we'll find some sort of ingredient that can be turned into food or gut loaded into live food with higher K+ ratios. Some of the potassium related salts are pretty non-toxic, maybe there's room for a potassium loaded food in the hobby that can function as a low tech fertilizer as well... people already drink KH2PO4 as Gatorade, and KNO3 was once used as a preservative. I'm pretty sure the ECOTOX database and other studies wouldn't indicate NOAEL's for either compound to be hit at anywhere near double typical standards. Making fish food isn't my idea of fun, but if anyone wants to try it out I'd be willing to do the math.

One of these days I need to put out an El Natural-EI hybrid just to annoy everyone besides perhaps those who created the methods. I'll call it EI Natural :snakeman:


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## goldier (Feb 13, 2010)

Philosophos said:


> People with well water are getting H2S directly from the well quite possibly. If it's a matter of SO4, the question would still be, "why is my substrate reducing sulfates at a significant rate to begin with?"
> 
> Another important question might be why Diana is saying it's dangerous to add K2SO4 when the ratio of potassium to sulfur is actually a little over 1% higher in the food outlined on page 79. I imagine the same issue would continue down on the light to anyone else who claims fish food is safe, but K2SO4 is not, as a matter of sulfate reduction.


Dan, good question, and good point about K2SO4 being perceived not as safe as fish food. Here are my thoughts:

With El Natural, soil substrate has lots of sulfate reducing bacteria (as compared to non-soil substrates). These bacteria need sulfur from sulfate as food to reproduce. When there are plenty of food (sulfate), the bacteria multiply exponentially, which can significantly increase sulfate reduction rate from the extra sulfate sources. This would be more problematic in the beginning of a setup when the plants have yet to establish themselves, and the sulfate in the new soil substrate is still abundant.

But a heavily planted tank can take in a good amount of sulfur (secondary macro) as plant nutrient from K2SO4. Some plants need as much sulfur as phosphorus. What little sulfate is left, if any, must be absorbed into the soil substrate to reach the anaerobic sulfate reducing bacteria to form H2S. When a NPT reaches equilibrium and achieves a balanced state with actively growing plants and substantial root system, the water pH is expected to remain neutral because acidic fish wastes and other wastes are quickly broken down by the plants. Plant roots and leaves take in sulfate to extract sulfur for nutrient; the sulfate reducing bacteria in the soil break down remaining sulfate into sulfur. If K2SO4 is dosed in such amount that plants absorb all the sulfate, there's no sulfate left for the bacteria to convert into sulfur. Since the water pH is very much at neutral, H2S gas if formed, does not dissolved entirely in the water, so it bubbles up and rises to the water surface - less water toxicity from the less dissolved gas. Long story short, for a stable tank, proper dosing K2SO4 should pose an insignificant risk of H2S toxicity, and benefit the plants with sulfur and potassium as the needed nutrients for their growth.



Philosophos said:


> You're doing El Natural with all the makings for high tech, just need to get you some CO2


Nice try to pull ObiQuiet over to the dark side  Although by not removing some decaying materials such as old leaves, CO2 injection is not necessary. If old leaves are removed due to aesthetic reason, peat moss or a similar carbon source can be inserted in the substrate periodically to help sustaining CO2 generation by bacteria.

Some thoughts on K supplement: Well, banana is very rich in K as mentioned by Edward. My plants, esp. roses love it. But we can't just put it in the water - perhaps using the clay ball idea Shurik brought up earlier is a possibility for dried banana crumbs. Spirulina is a good choice indeed. But it may depend on availability and how much the fish are willing to eat. I also think that fish food sources with K vary a lot, and many people don't make their own fish food, so it's hard to quantify how much is released in fish wastes. If the K amount in food is small, the fish may absorb most/all of it and excrete little to none in wastes so the plants starve K. A simple approach is to replenish some fertilizer with K (inorganic or organic) to supplement fish food as needed. The same goes for Fe and other micros after the plants use them up from the soil substrate.

Adding fertilizers may be frowned upon by the purists, but when the giving is less than the taking, the health of the whole aquarium begins to decline, first with the plants. Anyone who gardens knows that plants in pots or in the ground need fertilizers in certain amounts at least once or few times in a growing season to do well. Even with regular fertilizing, plants in pots need to be re-potted with new soil or replace surface soil with more fertile soil & composts (if the plants and pots are large in sizes) after a few years to maintain their health and vigor. The aquarium is a big pot that holds soil and plants and fish in it. In her book, Ms. Walstad mentioned the plants in pots declined after a few years - that is the same expectation as for terrestrial plants in pots - they would last longer if they were in the bigger pot, which is the aquarium.


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## ObiQuiet (Oct 9, 2009)

Great stuff, thank you.



Philosophos said:


> I didn't see the UV thing coming... that's a weird one given her cautious attitude about Excel's biocidal activity.


The principle is that the the UV only affects water-borne organisms, it can't touch the filter bacteria, biofilm, etc. Unlike a biocide, which gets everywhere. So I guess we can make the assumption that there are plenty of sources for repopulating the water column with the good stuff, and few sources of new pathogens.

From what you've said before, I understand not to worry about the build up of Cl from adding KCl. Some people add chlorine/chloride detoxifiers, though, to address it. Chemically, does that work? And if it does work, wouldn't those water conditioners also affect Mg? (Their labels say "removes chlorine and other heavy metals").


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## f1ea (Jul 7, 2009)

ObiQuiet said:


> Today's Measurements:
> pH 7.5, (steady)
> KH 89ppm, (down today from normal 107ppm)
> GH 125 (steady)
> ...


And you are worrying about a K and other minerals defficiency when you have 0 NO3? 

You need NO3. Try to get it to hang around 15-20 ppm via KNO3 dosing or increase your bioload. You can also maybe reduce the nap to only 2hr after you are dosing.

About your RO water... do you use RO as the main source of water or only the toppings? in any case, why not always use regular tap water for your tank? if your hardness values are above 10 dH GH and maybe above 4 dH KH, the minerals should be fine enough.

In the meantime, take care of the NO3 and see if it works.... maybe fish food, the soil and what's in your tap will keep the other nutrients available. So, just deal with NO3 at first and take it from there.

That's my opinion 

Cheers


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## ObiQuiet (Oct 9, 2009)

f1ea said:


> And you are worrying about a K and other minerals defficiency when you have 0 NO3?


Well, yeah, I am. At least until I read your post, that is! Thanks for pointing that out -- I'll be reading up on NO3, and it sounds like KNO3 is a better choice for me than KCl.


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## Philosophos (Mar 1, 2009)

goldier said:


> Dan, good question, and good point about K2SO4 being perceived not as safe as fish food. Here are my thoughts:


That's pretty much what I was thinking; unless the whole substrate goes hypoxic there's no reason for significant H2S to form in a harmful way. The layer of oxygen over the roots of plants should assure that any H2S formed isn't even remotely a threat. If it's forming so quickly that the substrate is bubbling H2S, then there's clearly too much in the way of organics. Personally I think it'd be easier to break an NPT in if people just mineralzied the soil, loaded it potassium-based salts, and then mixed back a little bit of organics to hang around until the mulm builds up.



goldier said:


> Nice try to pull ObiQuiet over to the dark side


It's what I do  CO2 has been a joy to put in my tanks; a tank that doesn't seem to need compressed CO2 suddenly becomes beautiful with the stuff.



goldier said:


> Although by not removing some decaying materials such as old leaves, CO2 injection is not necessary. If old leaves are removed due to aesthetic reason, peat moss or a similar carbon source can be inserted in the substrate periodically to help sustaining CO2 generation by bacteria.


Yes, I'm aware of the organic CO2 thing. It's a very good idea, one I intend to try out a little better if I ever do a tank free of sensitive fauna.



goldier said:


> Some thoughts on K supplement: Well, banana is very rich in K as mentioned by Edward. My plants, esp. roses love it. But we can't just put it in the water - perhaps using the clay ball idea Shurik brought up earlier is a possibility for dried banana crumbs. Spirulina is a good choice indeed. But it may depend on availability and how much the fish are willing to eat. I also think that fish food sources with K vary a lot, and many people don't make their own fish food, so it's hard to quantify how much is released in fish wastes. If the K amount in food is small, the fish may absorb most/all of it and excrete little to none in wastes so the plants starve K. A simple approach is to replenish some fertilizer with K (inorganic or organic) to supplement fish food as needed. The same goes for Fe and other micros after the plants use them up from the soil substrate.
> 
> Adding fertilizers may be frowned upon by the purists, but when the giving is less than the taking, the health of the whole aquarium begins to decline, first with the plants. Anyone who gardens knows that plants in pots or in the ground need fertilizers in certain amounts at least once or few times in a growing season to do well. Even with regular fertilizing, plants in pots need to be re-potted with new soil or replace surface soil with more fertile soil & composts (if the plants and pots are large in sizes) after a few years to maintain their health and vigor. The aquarium is a big pot that holds soil and plants and fish in it. In her book, Ms. Walstad mentioned the plants in pots declined after a few years - that is the same expectation as for terrestrial plants in pots - they would last longer if they were in the bigger pot, which is the aquarium.


The concept behind ferts (and UV for that matter) has always seemed to take the "natural" out of the equation. By the time the ferts and UV go in, you might as well strap CO2 to the system and call it a day. I think the challenge of El Natural/NPT is more in making a tank that doesn't depend on those things. Rather than that though, a lot of people just think it means an easier tank and they aren't purists about it. That's fine of course, but IMO it's not seeking to balance with natural substances to create a mostly self sustaining tank.



ObiQuiet said:


> The principle is that the the UV only affects water-borne organisms, it can't touch the filter bacteria, biofilm, etc. Unlike a biocide, which gets everywhere. So I guess we can make the assumption that there are plenty of sources for repopulating the water column with the good stuff, and few sources of new pathogens.


If these organisms are existing in an area with so little flow that it's hypoxic, I guess I'm wondering how significant quantities of something with an 11.5 hour half life is going to penetrate. That's the real question I have with all of this; substrate ORP and related kinetics. It's so ignored in the hobby that I can't find any resources that don't involve paragraph long equations in papers involving observations about rivers and lakes.



ObiQuiet said:


> From what you've said before, I understand not to worry about the build up of Cl from adding KCl. Some people add chlorine/chloride detoxifiers, though, to address it. Chemically, does that work? And if it does work, wouldn't those water conditioners also affect Mg? (Their labels say "removes chlorine and other heavy metals").


Chemically adding a dechlorinator to chloride means someone didn't learn the difference between chlorine and chloride. Don't worry, it's common in the hobby. Dechlorinators don't remove chlorine, they sequester it in a non-toxic form. Tossing an electron on chlorine converts it to chloride which performs basically the same function.



f1ea said:


> And you are worrying about a K and other minerals defficiency when you have 0 NO3?


My observation is that plants can't take NO3 down to 0 unless there's a whole lot of flow (river like); I've seen horrible nitrate deficiencies despite some NO3 always hanging around. I'd suspect the test kit is imperfect; calibration is something people need to start doing.

Even so, low NO3 doesn't mean that none has been added. If the plants are getting 22ppm water top off then they can be storing NO3 back. The K+ on the other hand is scant, so it's quite possible for it to be deficient. Either way, KNO3 wouldn't hurt if both are being bottomed out.


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## f1ea (Jul 7, 2009)

Philosophos said:


> It's what I do  CO2 has been a joy to put in my tanks; a tank that doesn't seem to need compressed CO2 suddenly becomes beautiful with the stuff.
> 
> Yes, I'm aware of the organic CO2 thing. It's a very good idea, one I intend to try out a little better if I ever do a tank free of sensitive fauna.


You're right about CO2. It easily makes things a LOT more beautiful and healthier growing. I guess it can be done totally with organic CO2, but it requieres much better planning and experience. And of course, there has to be some compromises.

Philosophos, I think you should try a El Natural tank. You certainly seem to know a lot about the inner workings of the planted tank... so you can definitely make some real comparisons about higher tech vs. natural. It could be interesting.

You want sensitive fauna? hmm in your case, maybe start it out with robust fish. Then after you see it stable, give some sensitive species a try... it should work.



Philosophos said:


> My observation is that plants can't take NO3 down to 0 unless there's a whole lot of flow (river like); I've seen horrible nitrate deficiencies despite some NO3 always hanging around. I'd suspect the test kit is imperfect; calibration is something people need to start doing.
> 
> Even so, low NO3 doesn't mean that none has been added. If the plants are getting 22ppm water top off then they can be storing NO3 back. The K+ on the other hand is scant, so it's quite possible for it to be deficient. Either way, KNO3 wouldn't hurt if both are being bottomed out.


Yes, the test kit can be defective. So DO make some sort of calibration. 
But even if plants cant totally drain NO3 to 0ppm, a reading could be 0-5ppm and the test 'shows' 0ppm. But in any case, it is possible and not uncommon, to have low NO3 readings in a planted tank. Specially using RO water and a low-ish bioload. Doesnt mean none is produced (NO3), just means its being uptaken.

The best is to add a known ppm of KNO3 (use the fertilator or Rex Griggs guide), then take a reading. No hobby test kit will be super accurate... but then again, what you need is to have some sort of idea of what's happening. No need to overstress with a super accurate reading. If you get readings within reasonable range and plants show no defficiencies... no problema.


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## Philosophos (Mar 1, 2009)

Some sort of natural tank is on my to-do list. I'll be going back over Ecology of the Planted tank and then maybe tweaking it a little. It's what I do; my first EI tank was stock solution dosed by my own PPM's, I'm not about to start doing anything by the book now. 

All my fauna is sensitive by default. Shrimp, apistos, otos, threadfin rainbows, etc. I tend to stick with the regular WC's for the fish interest as much as the plants. I do want to put together a low to no tech tank though; I've got it penciled in for after I learn sediment and ORP better.

If anyone needs fert dosing calculations or a double-check (KNO3 or otherwise) it's something I do very regularly for people. I do it often enough to have my own spreadsheets.


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## ObiQuiet (Oct 9, 2009)

Philosophos said:


> If anyone needs fert dosing calculations or a double-check (KNO3 or otherwise) it's something I do very regularly for people. I do it often enough to have my own spreadsheets.


I should take you up on that offer. I will be doing a large water change this week, so perhaps after that I can send you a PM?


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## Philosophos (Mar 1, 2009)

Sure, let me know what you want to accomplish and what sort of compounds you have. I've got a couple ideas for how to feel the tank out a bit better in regards to your lighting levels.


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## goldier (Feb 13, 2010)

Philosophos said:


> The concept behind ferts (and UV for that matter) has always seemed to take the "natural" out of the equation. By the time the ferts and UV go in, you might as well strap CO2 to the system and call it a day.


Strictly speaking from the true natural perspective: How "Natural" can it be if city slickers or someone who wants to be green would rather buy commercial soil instead of using natural soil in the woods? Adding UV contraption even makes it more un-natural. Fuggeddaboudit 



Philosophos said:


> I think the challenge of El Natural/NPT is more in making a tank that doesn't depend on those things. Rather than that though, a lot of people just think it means an easier tank and they aren't purists about it. That's fine of course, but IMO it's not seeking to balance with natural substances to create a mostly self sustaining tank.


Agree. Albeit the method such as El Natural, which is not 100% natural as the name implies, provides a step closer toward nature to achieve some sort of ecological balance in a closed system with less effort and less cost. Furthermore, the term "Natural" in El Natural is as romanticizing to its followers as Thoreau's adoration toward his Walden Pond in a beautiful spring morning 

In nature, alluvial sediment movement into ponds, the deltas such as those of the Mississippi's or the Mekong's renew and replenish nutrients to them year round. In the context of El Natural, the tank is sustained with fish food, or by adding Epsom salt, or Ca source in the water to maintain certain hardness level as they are used up by plants. It can be argued that adding salts & fish food is neither a natural act, nor the prepared food itself a natural substance. For many non-purists, the end justifies the means.


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## Philosophos (Mar 1, 2009)

The question of which part of nature is being replicated is rarely even addressed, and the romanticism is worrisome when it comes on that early. While I can appreciate that any number of plants from different continents can get along just fine, I think a plant that likes a stream will have different needs and behaviors than a plant that lives in a marsh, and that morphology between these conditions can change the plant entirely.

I really need to get a post done one of these days covering a foray to a local eutrophied drainage system and river covered in Ludwigia palustris to show why all of this matters to a hobbyist trying to say they're doing something natural. Within a 5-10 minute walk you can see the stuff start from a classic stem with big round leaves looking something like L. cardinalis to a floating carpet, emerse its self to creep and flower then let out a fine carpet of plantlets. Walk a little farther and you'll see it growing off of a rusty old pump in near aeroponic conditions into jagged leaves resembling none of the past growth forms. You can see all of this, and every step in-between with thousands of examples. Take it home, clean it up and you'll find under more typical aquarium or terrarium conditions it looks little different from your average stock of L. repens; something it didn't resemble under a multitude of environments in nature.

A lot of people have been disillusioned about just how natural their tank isn't, and the harsh wake-up turns them to high tech prematurely or leaves them on the sidelines saying they like a simple tank and they do what works. That's fine with me if it's what they really want, but it'd be nice if more people went back the other way. Observing plants in nature and learning how to make them grow in ways we don't see in the hobby is precisely why I value the attempt to recreate natural conditions. I may not be experienced with it (yet) but it's something that seems to have passed by the hobby.


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