# Nutrient Inhibition Discussion Thread



## BryceM (Nov 6, 2005)

Since I've become seriously involved in this hobby (only two or three years ago) I've seen countless posts and ideas regarding "the best" way to dose nutrients. Most of the "information" that is out there is little more than anecdotal observation, made by various people at various times under highly variable conditions.

For good or ill, the concepts behind the "EI" method of dosing have become pretty well established in the hobby. The general theme behind this method is to dose each nutrient in excess of what is needed to ensure that no deficiencies result. Toxic concentrations are avoided by regular waterchanges. This excessive nutrient dosing is regarded as perhaps wasteful, but certainly harmless.

Without getting into a war about EI vs. "your particular method" I'm wondering if this excess really is "harmless".

The interplay between nutrients is quite interesting and is something that I've been paying more attention to lately. There is some evidence to suggest that high NO3 or K concentrations can cause Ca or Mg deficiencies to manifest themselves, even when these elements are abundant. Likewise, PO4 reacts with some forms of Fe to create an insoluble compound that may or may not become bioavailable to the plants in the root zone. There are countless other potential examples. Many people have commented on "differences" in nutrient behavior under high GH/KH situations.

A look at most natural water sources will reveal that most aquatic plants live and even thrive in an incredibly dilute water column with a comparitively rich substrate. Certainly the VAST, VAST majority of plants grow in waters with nitrogen and phosphate levels that are orders of magnitute less abundant than in our aquariums.

Much has been said about the ideal Ca/Mg ratio and the ideal NO3/PO4 ratio. Are these ratios actually important? If so, why? Isn't it sufficient to have "enough" of each nutrient available?

Recent posts by many users have described succesful setups that do perfectly well with quite lean macro & micro dosing as compared to typical EI "standards". 

My personal bias is leading me to believe that small additions of macros are sufficient if (and only if) they are dosed regularly. I'm also starting to believe that macro nutrients from the water column accumulate as a tank matures to become concentrated in the substrate. Wouldn't this easily explain why ADA substrates help jump-start a tank? Aren't most "mature" tanks easier to maintian? 

Anyone care to comment?


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## jeff5614 (Feb 15, 2006)

I'm really looking forward to the responses on this topic.


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## Avalon (Mar 7, 2005)

This is a fantastic question, one I've thought about for quite some time. I've even set up tanks to experiement with, and have even done so on my own 'personal' tanks. The EI method in it's truest form is overrated, however, it's fundamental teachings are very important to serve as a foundation for every aquarist. Every tank needs macros, micros, and most importantly, CO2. *CO2 is a nutrient, the most important of all!* Sure, you can get away with it, but it's not 'proper (imho).' Why go to all the effort to grow a plant when you can grow a 'great' plant?

I've been pointing the finger at the EI method for a while now, reasoning that you don't need nutrients in such excess. All you need is 'enough.' Certainly, there is care to be taken by every responsible water plant owner to look after water column conditions to ensure no blatant deficiencies. Again, thinking in earthly terms, the substrate is a foundation upon which to build skyscrapers--a haze of smog doesn't do them justice--as you need nice clean air to witness such a wonder.

I've found nothing but a train wreck waiting to happen in super high light tanks with 'excess' nutrients. You may make good for a while, but reaction time diminishes greatly. All I've noticed is enhanced algae issues. All this extreme hair algae, fuzz algae, green dust--it's all related to nutrient/light imbalances. Think about it: would you rather take your chances and get slammed with algae and try and clean the mess up, or have some time to notice something is wrong and react appropriately without things getting out of hand, avoiding a disaster altogether? People get excited and want to impress, so they start haphazardly dumping nutrients in their tanks, upping the light, and CO2 without a care in the world because "that's what x said." We must be responsible for our own tanks, using the proper hardware, dosing only the necessary nutrients for our own specific conditions. Therefore, we must all become investigators, discovering the plants we like best and the best enviornment to suit them. Then, and only then, can we develop a plan of action that suits ourselves. We underestimate the plants at times I think. Like humans, they need a well-balanced diet, free of excess.

I've yet to find any proof that a 10:1 type ratio is necessary, nor any other for that matter. Naturally, your going to get a similar ratio, as that's just the way it works. When pressed hard, flaws will become readily apparent, and overreaction ensues. In other words, when driven with excessive light, deficiencies become apparent, and we overreact by dumping more nutrients in. So, slow things down with less light, and I am 100% positive that good results will come of it. Carefully matching the proper light on the proper tank with the plants of our choosing is essential to success.

I'm not bashing on EI, but I am and always have been concerned about such a simple "solution." I once proposed that we educate ourselves with the fundamentals of planted tanks and tailor them to our own needs, and I got ripped by a certain person for it. The way I figure it, we need to think for ourselves and exert a little effort--it does go a long way. I suspect that if the EI is the be-all, end-all, we wouldn't be having this discussion and everyone would have a perfect planted tank.


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## Glouglou (Feb 21, 2006)

Personally, I’m coming back to a leaner way of fertilizing. Based more on nature itself. (You can’t go wrong).

(It will be very interesting to have a post with the analysis of natural water by biotope and if it’s possible the soil composition.)

Lean water column and rich substrate, good circulation, CO2 injection.
Something around the parameter of Kekon finding:
Ca = 10
Mg = 4
PO4 = 0.1
NO3 = 2
K = 15
CO2 = 10 very fast growth,
no stunting at all,
heavy micro dosage, high iron demand
no NO3 dosing at all 

Remark that those numbers are almost what Sears and Collins was saying with their PMDD some time ago.
PH — 6.5 / 7
Tempº — 76º / 78º
Filtration — 3 to 5x volume / hour
CO2 — 20 ppm / 40 ppm
KH — 30 / 50 ppm
GH — 40 / 120 ppm
Mg — 5 to 10 —>45 ppm
NO3 — 5 / 10 ppm
P04 — .4 / 1 ppm
K — 20 à 30 —>50 ppm
Fe — 0.1 ppm PMDD (.2 to .5)




I’m trying to develop a easy way to calculate the consumption of nutrients on a any particular set-up and dose a little bit over that.

To calculate the dosing regimen on the consumption is a sure way to adapt fertilizing to each personal set-up.

I think we have to pay attention of the plant ability to stock certain nutrients, some until 1000 times (like Oligo and NPK) and some less like calcium, magnesium and sulphur, and the content of these by plant mass.

When we used high dosing of nutrients it will work for some time and, when the plant reserve is full, problems of nutrient deficiency by blockage will happen. At this point all the dosing regimen that was working perfectly become our plants demise.

For the induce deficiency, I have that so far.
Ps: most of them you can reverse the equation

Excess amoniac / ammonium = potassium and iron deficiency
Excess potassium = calcium, magnesium and iron deficiency
Excess sulphur = molybden deficiency
Excess Iron= manganese deficiency
Excess cooper = iron deficiency
Excess magnesium = iron deficiency
Excess nitrogen = potassium deficiency
Excess phosphorus = potassium deficiency
Excess magnesium, potassium or sodium may = calcium deficiency

Excess boron marginal and intervenal scorch which may be confused with potassium or magnesium deficiencies

Sodium and chlorine may cause marginal leaf scorch similar to potassium deficiency

Excesses of chromium, cobalt, copper, manganese, nickel or zinc may induce iron deficiency


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## Tonka (Mar 20, 2004)

All fertilizing systems (EI, PPS, Seachem, ADA) attempt to provide a one-size fits all method of growing aquatic plants. Each makes different implied and explicit assumptions regarding water chemistry, light, types of plants, substrate, and most importantly, the willingness (or lack thereof) of the hobbyist to test, change water, and / or incur expense.

Compared to our tanks, nature provides a virtually infinite and nearly consistent water column with much lower concentrations of nutrients. A plant in nature doesn’t have to contend with high levels of rapidly fluctuating nutrients causing uptake inhibition or even toxic responses via secondary metabolic pathways. And why should we even try to figure all this out? There may not even be a “sweet spot” when concentrations of everything are so unnaturally high and changing all the time. 

I think we would all prefer to use natural conditions in our tanks – if that would work. But we know that if nutrients are depleted, plants stop growing and algae takes over. And nutrients can be exhausted very quickly in our little glass boxes.

Every day my tank consumes 1 ppm of NO3, 0.6 ppm of PO4, and 0.6 ppm of K – all measured with LaMotte test kits. If I were to dose PO4 only every other day, I would have zero left before every addition. So I dose KNO3 and Fleet every single day (as well as Fe and CSM+B).

Glouglou’s point about plants storing nutrients is still another variable. I would expect to see one or another of my consumptions to drop when my plants stores are full. Actually, maybe I saw this because until a few weeks ago my daily NO3 consumption was a steady 2 ppm. When the concentration of nitrate in my tank increased unexpectedly, I immediately lowered my dosage to reflect the lower consumption which has held steady ever since.


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## BryceM (Nov 6, 2005)

Tonka, care to clarify what your usual water parameters are kept at? What are your "goal" levels and how much do you add daily?


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## Tonka (Mar 20, 2004)

Targets (ppm):

NO3 15
PO4 1.5
K 20
Fe 0.5
CO2 35+ (drop checker; pH controller set at 6.1-6.3)

Daily adds (ppm):

NO3 1.0 (KNO3)
PO4 0.6 (Fleet) 
K 0.6 (KNO3)
Fe 0.25 (Chelated iron and CSM+B)

My plants are growing quite well, with no apparent deficiencies. I have small, tolerable amounts of every kind of algae there is and change and reset 30% of my water every 15 days.


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## johnzhou2476 (Nov 28, 2006)

Tonka said:


> Targets (ppm):
> 
> NO3 15
> PO4 1.5
> ...


Hi Tonka,

When you reset your tank at 15 days interval do you overdose your Macro & Micro to get your nutrient level up after the water change?

Thanks,
John


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## johnzhou2476 (Nov 28, 2006)

Tonka,

How much Flourish or Flourish Equivalent to you dose in ml per day? I have a very similiar setup as yours and would like to follow your dosing routine. 

I have a 110 gallon which was recently torn down and redone. My tank is 4" wide and 30" tall. Two Eheim 2028 pro, Hydor set at 76 degree, CO2 at 30ppm, GH=1, KH=2, PH=6.2. All Flourite substrate at 3" deep. 10 medium large rainbow fish, 20 Rummy nose, 20 Cardinals, 10 SAE. Moderate feeding.

My tap water has 2-3ppm, so I don't dose Phosphate. Currently, I'm changing water every week but would like to extend that to 2 weeks. After 50% water change, I add 1 tsp of Potassium Nitrate and 1/4 tsp of Potassium Sulfate. On odd days I add 5ml of Flourish and 2ml of Flourish Iron. On even days, I add 1/4tsp of Potssium Nitrate and 1/16 Potassium Sulfate. I stopped adding Equilibrium and Baking Soda - the result seems to be an improvement. 

My tank has been only setup for about 2 weeks now and my plant mass is still small so I'm doing a fraction of full EI dosing. My photoperiod is 9 hours at 265watt and 2 hour midday blast at 460 watt. 

How should I tweak my dosing routine to keep up with my evolving tank? Obviously the tank will mature and gain gretter plant mass - the challenging part for me is tweaking my dosing to adapt to the changes in my tank.


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## Tonka (Mar 20, 2004)

The night before my water change I add enough CaCO3 and MgSO4(7H2O) so that when I replace 30% with RO I reachieve my target GH of 4. I then add enough KNO3, Fleet, iron, and CSM+B to bring NO3, K , PO4, and Fe up to my targeted levels. I test the water before adding RO to see how much I will need to add.

The attached spreadsheet might be helpful, but please understand the algorithms before you rely on it for dosing....


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## Bert H (Mar 2, 2004)

This is very interesting. But the main problem in trying to relate cause and effect is that strict controls must be adhered to which few of us in the hobby end of things, are able to accomplish. Let's say you want to see what happens to Ca uptake if you increase K. You need at least 2 tanks you're willing to play with and possibly sacrifice to algae or whatever. Then you need to vary concentrations, while maintaining all else the same. Start looking at multiple nutrients, and you can clearly see the logistical problems for the average hobbyist. 

In the meantime, we have lots of empirical observations, which we have difficulty proving or correlating because all our waters, routines, etc are different. 

In my case, for example, I have hard North Florida well waters rich in calcium carbonate, very low in magnesium. I add magnesium to my tanks. I have moderate lighting. I also add extra potassium. I still have stunting in A. reinickii. Sometimes it doesn't show up for months, but then, for no apparent reason, it's there. I'll tweak something and make believe it's fixed it, at least until it happens again. Eventually, I realize, that I need to be relatively satisfied with things the way they are, and keep fine tuning all the ferts according to the overall health of my tank. Currently, I am going away from heavy water column dosing. 

I have decided to turn my 10 gal tank into a bit of a 'research station', so to speak. I am going to plant it like a 'farm' with rows of various plants. I want to look at micro dosings. I figure if I screw it up, it's only 10 gallons, and it's easy to tear up and re-do it. Hopefully I will learn something I can apply to my 50's.

This is one of the facets of a board like this which is so helpful. We can all learn from each other, while hopefully realizing, our results are not all going to be the same, and that noone has 'the answer'.


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## BryceM (Nov 6, 2005)

Let me steer the discussion a bit. Many people have noted that aquariums with hard water often require/tollerate higher macro & micro concentrations. Any ideas about what mechanisms would be responsible for this observation?


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## Bert H (Mar 2, 2004)

> Let me steer the discussion a bit. Many people have noted that aquariums with hard water often require/tollerate higher macro & micro concentrations. Any ideas about what mechanisms would be responsible for this observation?


I am one of those who has felt that way. However, in an attempt to correct some green dust issues in one tank, I have cut back macros. The green dust has abated. At this point, however, I am not sure that the Blyxa japonica in the tank is as happy as it was. Hopefully in another month or so, I will have a better feel here.

Why the higher levels with hard water, I haven't a clue. Perhaps plant physiologist can offer some insight into rates of uptake or enzymatic reactions under different Ca/Mg/CO3 levels.

We have lots of springs and spring fed rivers here in N. Florida. All are fed from the Floridan aquifer which is a limestone aquifer - heavy Ca, very little Mg. Water is relatively lean in NO3 and PO4. There are beautiful plants growing through the springs. When nitrates and phosphates increase, algae shows up and it makes the paper as news. Nutrient concentrations in the substrates, I don't know.

One thing to remember is that in nature, there is a niche where certain plants flourish while others don't. In our tanks, we try to make it so that every aquatic specie under the sun will flourish. There's a paradox there, no?


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## BryceM (Nov 6, 2005)

Bert H said:


> One thing to remember is that in nature, there is a niche where certain plants flourish while others don't. In our tanks, we try to make it so that every aquatic specie under the sun will flourish. There's a paradox there, no?


Maybe you can get them all to flourish but I sure can't


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## Bert H (Mar 2, 2004)

> Maybe you can get them all to flourish but I sure can't


Neither can I.


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## defdac (May 10, 2004)

> Let me steer the discussion a bit. Many people have noted that aquariums with hard water often require/tollerate higher macro & micro concentrations. Any ideas about what mechanisms would be responsible for this observation?


Higher pH means more OH- means more Fe(OH)2 and Fe(OH)3 precipitate which ups the need for more Fe-dosages.

This is why copper is less toxic with high KH/alkalinity.

Chelates also binds harder to their metal with higher pH making the metal harder to extract for the plant.

So does lower pH/KH make NO3/PO4 more toxic, even to plants? Is plants more sensitive to PO4/NO3 than fish? Would you see the toxic effects of NO3 and PO4 on the fish or the plants first?


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## LindaC (Nov 7, 2005)

This is fascinating. I have been posting about the stunting my plants have been going through and the fact that I was seeing no growth (Rotala Indica) at all in some of my plants and was wondering it I was adding too much nutrients to my tank with EI, regardless of the 50% water change every week.

Then when I started seeing BGA, a red flag went up that maybe 1/4 tsp of KNO3 three times a week under 2.23 wpg of light, even with CO2 injection was too much. It was giving me atleast 40 ppms of Nitrate, maybe even more, which I believe is too much. The plants weren't taking it up fast enough.

In just the last two weeks I have started dosing much less ferts, adding more water circulation and I'm now beginning to see better growth.


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## jeff5614 (Feb 15, 2006)

LindaC said:


> This is fascinating. I have been posting about the stunting my plants have been going through and the fact that I was seeing no growth (Rotala Indica) at all in some of my plants and was wondering it I was adding too much nutrients to my tank with EI, regardless of the 50% water change every week.
> 
> Then when I started seeing BGA, a red flag went up that maybe 1/4 tsp of KNO3 three times a week under 2.23 wpg of light, even with CO2 injection was too much. It was giving me atleast 40 ppms of Nitrate, maybe even more, which I believe is too much. The plants weren't taking it up fast enough.
> 
> In just the last two weeks I have started dosing much less ferts, adding more water circulation and I'm now beginning to see better growth.


Linda,
Isn't BGA associated with low levels of nitrate? How much less are you dosing now?

I've not measured my nitrate level in a long time and finally decided to today. I've dosed approx 12.6 ppm nitrate since doing my weekly 50% WC on Saturday and when I measured today I'm at 15 ppm according to my AP test kit. So it seems I am accomplishing the goal of EI and keeping an excess of nutrients in the water column but I'm wondering is an excess necessary. I'm not trying to turn this into a debate over any dosing routine. I'm just curious if the excess levels are needed.


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## LindaC (Nov 7, 2005)

I've read that BGA can be assocaited with low levels of nitrate and high levels of nitrate. Also stagnant water or poor water quality. Seeing that I do 50% water changes, sometimes even more, once a week, I doubt poor water quality is the culprit. I have a powerhead in my tank now to keep the water moving. I've cut my dosing of KNO3 and KPO4 in half.

Keep in mind that I have a pretty heavy fish load and tend to be a little heavy handed when I feed them too!

I will try this schedule for a couple of weeks and see what happens, if I don't see a significant change, I will go back to dosing more but I do think that my nitrate levels need to come down a bit.


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## BryceM (Nov 6, 2005)

Just for a point of reference, five or six years ago the idea of actualy adding nitrate to a planted aquarium was regarded as crazy. Nitrate was viewed mainly as a waste product of the nitrogen cycle and secondarily as a plant nutrient. A few people were using it, but it certainly wasn't mainstream.

In a medium light tank with a heavy fish load you could probably get away without dosing any. How's that for a radical notion?


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## defdac (May 10, 2004)

Lowtech Walstad tanks certainly can, but they have twice as much fish and ten times lower growth rates than a hightech high CO2 tank.

You can calculate the amount of fish food you dump into the tank and it's protein content and then come up with a fairly exact amount of NO3 you get from that protein. (1 gram of protein => 0.7 grams of nitrate if I'm not mistaken)

I feed my 10 fish a flake (milli or microgram?) every other day in my high tech - others with lowtechs/Walstads dump in several grams of live and flake food several times a day. 

Apples and pears. 

You can't rip out more energy (in the form of plants) than you put in (in the form of light, food and/or inorganic nutrients).

So how do I guarantee that my plants have the nitrogen they need? Probably by some continous add/flow of nitrates in some form. If you know how much nitrate you get from fish via bacterial activity and how much your plants remove when you have a certain amount of plants (slow or fastgrowers?) and a certain amount of light (hours per day? intensity? how much self shading?) for a certain amount of CO2 and temperate and how much you subsrates CEC sucks up it's ..... easy(?).... to just add that amount.

But wait. That's close to impossible to know and measure?

So why not add a buffert of a bit higher than normal nutrient levels? The plants can get what they like and fill their storages as much as they want. When they are finished noone knows how much nitrates are left. Flush everything and add everything back.

*shrug*



Linda, I've also seen more Cyanobacteria when I've dosed too much KNO3, as I've seen them when having very low nitrate levels. Could it be that bad circulation and high NO3 means less oxygen and more DOC and happier denitrification bacteria which in turn means more N2/ammonia which triggers Cyano growth?


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## defdac (May 10, 2004)

Another thing to ponder is the TDS-levels in hydroculture. Roots exposed to about 1000 ppm. No inhibition there. Are roots less sensitive compared to underwater leaves? Even if under water leaves were more sensitive to higher TDS and therefore nutrient inhibited, why would the roots be inhibited?

The more I think of it the problems folks are having with higher nutrient concentrations must be related to the inaccurate Liebig-theory - when you eliviate some of the macro-inhibitions with higher NPK (easiest to dose) other less water solouble micronutrients becomes the growth rate inhibitors. Boron comes to mind - looks like Calcium deficiency. 

Let's for arguments sake say that Calcium can be the one single show stopping nutrient under high light/CO2/NPK/Micro. Or CO2 as Tom Barr would have said. The best thing to do in that case is not to dose more, but to limit growth rates in some way. Light-duration/intensity comes to mind as being the most effective...

If others think NO3/PO4 *shrug* Whetever works I guess..


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## BryceM (Nov 6, 2005)

New plants often take a few weeks to establish themselves and start growing. I've seen a few people here offer the opinion that the "period of acclimation" is the time it takes the plant to grow a root system. This certainly seems to be true for plants like Blyxa and various crypts. Even Anubias and java fern seem to grow faster/better if the roots are allowed to grow into the substrate.

Perhaps plants are capable of nutrient uptake through the leaf, but only when certain ratios/conditions are to their liking. It seems plausable that local chemical conditions in the root zone (increased acidity) might make the nutrients in that region more bio-available. The physiologic ability of the plant to extract nutrients in the root zone is probably also higher than in the leaf system. Still, it's clear that water column dosing works - but maybe just not as well as natures way.

Maybe I'm just stating something obvious, or maybe it's even something that has been shown to be untrue. I certainly don't want to steer the discussion toward the mertis of substrate heaters or use of RUGF's. Those have already been discussed to death. There's no denying the fact that chemical conditions are different in the root zone though.


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## Troy McClure (Aug 3, 2005)

I like this thread. BUMP!


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## BryceM (Nov 6, 2005)

I recently cut my dosing of potassium to 20% of its former level. I cut my KNO3 dosing by 50% and also reduced my KH2PO4 dosing. Many more species of plants are now doing well for me, including L. 'guinea', P. stellatus, and R. macranda. Other plants seem to be more robust too. Algae issues are declining.

Admittedly, many changes are still taking place in my tank since it's still a pretty new setup. Many other confounding factors could make these only anecdotal observations.

Whaddy'a think? The topic still interests me quite a bit.


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## Kelley (Aug 27, 2006)

I am curious to know how many people continue to use EI as a long-term fertilization strategy. It seems like many people abandon it after things get going in their tank. 

**Note: This is not a critique or an endorsement for any particular regime or it's proponents/inventors. I'm just a curious beginner.


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## Bert H (Mar 2, 2004)

A little info, FWIW - I had cut back on my nitrate dosing on my tanks to once a week at water change. I measured levels with a calibrated Hach kit, and by weeks end the nitrates were in the 5-8 range after starting in the 10-15 range depending on the tank. My B. japonica suffered, and for whatever reason, I got some algae on Anubias leaves which never had any before. So now, I have gone back to twice a week dosing, and the Blyxa is growing again. The stuff on the Anubias seems to be disappearing. 

I mention all this because in the past, I had always 'felt' like hard waters (which I have) seemed to require higher fert levels. This would give credence to that.

I would have thought that 5ppm of NO3 would have been sufficient to not cause problems. I have Blyxa in all 3 tanks and all of them experienced problems. The algae was only seen in one. As I said, FWIW.


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## Avalon (Mar 7, 2005)

Kelley said:


> I am curious to know how many people continue to use EI as a long-term fertilization strategy. It seems like many people abandon it after things get going in their tank.


I think that EI is a fundamental method of fertilizing a planted aquarium and is simply a catch phrase for what most of us would figure out and do without actually being told. What I don't like are the set dosing amounts for x size tank, because frankly, it's not necessary and it does cause problems. It's up to the tank owner to know what the tank needs and dose accordingly--that's the key to a successful planted tank--consistency in moderation.


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## Left C (Jun 14, 2005)

My college library has a book that has some good information that can be applied in this discussion. I haven't read it all yet. I ended up buying a used copy on Amazon.com. I just want to let you know the name of it.

The name of the book is:
Water Quality in Ponds for Aquaculture by
Claude E. Boyd, Ph.D., Professor
Department of Fisheries and Allied Aquaculture
Auburn University
Auburn, Alabama

Amazon.com: Water Quality in Ponds for Aquaculture: Books: Claude E. Boyd

This professor has written quite a few books dealing with the various aspects of aquaculture:
Amazon.com: Claude E. Boyd: Books


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