# [Wet Thumb Forum]-No more Potassium !! (new approach ?? - read more)



## lsuber (Dec 15, 2003)

I have two questions regarding the chemistry of using pure fertilzer compounds like those found at www.plantgeek.net. First, do you not get the benefit of added potassium by adding potassium nitrate? Why the need to add potassium in another form? Second, in adding postassium sulfate, where does the sulfate go? Seems to me that free sulfate would lower the pH (even by a small amount). Just wondered where that part of the chemical goes. I'm fairly chemistry-literate, so you can lay the jargon on me.

[This message was edited by Jay Luto on Sun January 04 2004 at 12:41 PM.]


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## lsuber (Dec 15, 2003)

I have two questions regarding the chemistry of using pure fertilzer compounds like those found at www.plantgeek.net. First, do you not get the benefit of added potassium by adding potassium nitrate? Why the need to add potassium in another form? Second, in adding postassium sulfate, where does the sulfate go? Seems to me that free sulfate would lower the pH (even by a small amount). Just wondered where that part of the chemical goes. I'm fairly chemistry-literate, so you can lay the jargon on me.

[This message was edited by Jay Luto on Sun January 04 2004 at 12:41 PM.]


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## Roger Miller (Jun 19, 2004)

Some people find that the amount of potassium provided by potassium nitrate is not enough to satisfy the plants' demands for potassium. That is why some formulations add additional potassium from potassium sulfate. I don't find that to be necessary.

The sulfate from potassium sulfate (or magnesium sulfate, or calcium sulfate, etc) enters solution and stays there. It has no effect on pH. pH measures the amount of hydrogen ion present, and sulfate provides no hydrogen ion.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## Guest (Dec 29, 2003)

Roger,

Are you a member of DFW ?. We are having great discussion on our forum with detail information re Potassium/Calcium.

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Regards,
Jay Luto


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## lsuber (Dec 15, 2003)

I knew that the sulfate group brought no H+ of it's own to be ionized, but neither does the CO2 from a cylinder, yet through other processes it lowers the pH of the water (via formation of carbonic acid). Just curious is all. 

I did place an order through plantgeek yesterday and will be experimenting with pure additives from the beginning with the new tank!


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## Roger Miller (Jun 19, 2004)

Jay,

I'm not a member of the DFW club. Can you summarize the discussion for us?

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## Guest (Dec 29, 2003)

> quote:
> 
> Originally posted by Roger Miller:
> Jay,
> ...


Here is observation or actually detail information from Ben Belton (with his permission).

Potassium Dilema

*March-August * 
Soon after I moved into my new house, I bought a 75 gal tank. It was finally all set up around the middle of March. I tested the GH in the tap water, and it was low so I began to add some Seachem Equilibrium (Ca, Mg, K, Mn) with water changes. My plants did great, but adding Equilibrium is a pain in the butt. Since I had more tank space, I naturally bought new plants and received others from friends. Some of the new plants were Ammania gracillis, Nessea sp., and Tonina sp. I had the Ammania a couple months before getting the others and it did great for awhile, but eventually started to decline. The Nessea never did well and the Tonina actually died. Some other plants I already had that did OK were Eustralis stellata, Rotala magenta. Rotala wallichi, and Hottonia. E stellata never does great for me, but it was surviving.

*September * 
I had some family drama this month, and I'm lucky everything in the tank didn't die. Ammania was doing terrible with crumpled up leaves, Nessea must be dead, I can't find it, Tonia- dead, Rotala Magenta- barely surviving, R. wallichi- making it, but not thriving, Hottonia is just existing but about dead, and E. stellata is about all dead. As usual, most plants seem to be immune to whatever causes the problems in the other plants. I figured part of the problem was that I was keeping my nitrate dosing low to keep from having algae. Also, the lighting seems dimmer in the 75 than in my other tank, and I'm not used to working in lower light tanks. I was skeptical that could be the answer though because other people grow these plants very successfully in half the light I have.

*October * 
At the GWAPA meeting in October, a couple of us discussed the need for all the K that we have come to think of as the standard level. I think I brought it up, but seems several of the others had been thinking about it too. Ghazanfar had found that K and Ca compete with each other for uptake in plants, so he felt that if you had too much potassium, it would inhibit the Ca from being absorbed. I was glad to meet Jeff Ludwig and Jay Luto and they had similar thoughts. They basically convinced me to think about ditching all the K dosing. This month I found more Tonina and was looking forward to trying it again and I also received more E. stellata from Luis.

*November * 
At the AGA conference I was glad to see Ghazanfar and Jay again and finally met Phil Edwards. There were more discussions about decreasing the K in our tanks. Also, on several slides that Cristel Kasselmann presented she showed the water chemistry for the water in the areas where she collected some of her plants. I think the highest potassium level she found was 3ppm. While this was a very small sampling of habitats, it gave more credence to our forming potassium theory.

In my tanks at home it was my plan to take all the plants out of the 40gal and start doing some aquascaping instead of all this plant farming that I have been doing. All the species that I didn't really need or were readily available from friends would be thrown out and everything remaning would be moved to the 75 gal. Also, I decided that I would not add any more K except that which comes from the KNO3. In the past I had added 20-30ppm K plus the K that came from Seachem's Alkaline Buffer, plus that which came from KNO3.

So after the conference I came home and took all the plants out of the 40 gal and the 75 gal. I threw away the plants I did not want and replanted the ones I did. I was surprised to find some mangled stems of the Nessea. I thought it had died and was amazed to find anything left. There were almost no leaves, they stems were green and brown, and only about 3" tall.

It was in the week I was working on all this that I had a revelation. I couldn't understand why my Ammania that had done so great early on, had been doing terrible for months now. Then I realized something that I felt stupid I had not realized before. A couple months after starting the 75 gal, I had again tested the GH of my tap and it was up. I know that these things can fluctuate seasonally. I had stopped adding the Equilibrium and had not in months. No Ca and very high K.

So, in the re-setup of the 75, I dosed no K except that which came from KNO3. I have been trying some Seachem Nitrogen since I had some free bottles and dosed a tiny bit of K then, but I didn't use the Seachem Alk buffer. This was from being slack more than from wanting to avoid K. I just didn't have time to test KH and out of the tap it's about 3 anyway which isn't too bad. I also bought some Turbo Calcium and began adding about 1/4 tsp of that at water changes.

So to summarize, I was adding about 1/8 the K I had been and now adding a small amount of Ca. Within 48 hours I could tell a difference in my plants. There was new healty growth from the Ammania and ***the Nessea!!!***. The Rotala Magenta sprang to live, the Hottonia was putting out new healthy growth and the Tonina stopped dying. It was amazing. I was adding nitrogen and phosphorus to my tanks and the E. stellata never stunted. I was surprised. I even added a couple large doeses because that was normally all it would take to make this plant wither. It never blinked.

*Middle of December * 
At this point all the above plants had been doing great for about a month. All were growing and putting out new leaves. The Tonina actually had new growth. I have never had new growth on that plant, and I was excited. Remember the first time I killed it. This time it was actually growing.

Then the week of Dec 7th I messed up. On water changing day I added a small amount of K2SO4 because I knew I would be using the Seachem nitrogen. Also, I decided to try not to be slack and add some Alk. Buffer. I didn't think about the potassium in it until after I added it. I didn't worry much about it because I didn't think there would be that much K, but in 48 hours, everything had gone downhill. The E. stellata and R. Wallichi crumpled and the Nessea had developed some curls in the leaves by the end of the week. The Rotala magenta stopped growing. The other plants don't seem to be as dramatically affected so soon.

*End of December * 
I have added too much Seachem Nitrogen and got algae and green water. It took a couple weeks and some water changes, but most of the algae went away. With the water changes I started using Equilibrium again, no Alkaline Buffer, and no K2SO4. The trouble plants have taken back off like they were at the beginning of the month and everything is back on track with nice growth.

*Things to Think About * 
1. Note all the last month when I was having the great growth, I was not adding anything to increase my KH. The growth might be because the plants prefer a lower KH and not a lower potassium.

2. Sechem Equilibrium has a significant amount of potassium in it. If potassium is the problem, why do the plants grow good in Equilibrium too. Maybe the issue is a balance between K and Ca. Not one of excesses. An excess of K might be OK as long as there is plenty of Ca.

3. I believe it is still way too premature to draw any conclusions from my experiences, but it is definitely something worth exploring further. I need to use just Equilibrium for a few months, then the Turbo Calcium for a few months, and compare. As it is, I want my plants to do good and don't have the patience to try one or the other for long periods while one method is doing good.










*Reply from Jeff Ludwig*
Good post Ben... about 'natural water' parameters... this is why I'm so eager to try Amano/Navarro-type fertile substrate... from plants in S. America at least, conductivity of the water is near zero, it's basically RO water juiced up with CO2 from rotting plant matter IIRC...

I'm certainlly not going to claim plants don't need N/P/K, its just the very fertile soils in rivers/ponds provide most of this methinks... So without a fertile/soil-like substrate, I don't know if you can runs things as low as Kasselmann reports/typical waters, but see upcoming thread about Wheeler's 20 gallon, it defies logic... the aquarium is a rather artifical environment, know what I mean? I think its important to get all the elements correct if your going to run things like rivers...

G will prolly chime in here, but on the GWAPA forums at least word is that a 4:1 Ca to K ratio seems to be magic to eliminate competition, dunno if this K+ to Ca2+ or K+ to CaCO3 ppm... this all makes sense since Tom worked with liquid rock when he developed these techniques, so I'm sure he found K+ needed to be really high.

*Response from Phil Edwards*

Thanks for that little journal, it's interesting to read other peoples' accounts of their regimens and the affects on their tanks. I had the same problems with Nesea c. and Limnophila a. in my tank a few months ago, before AGA. I wasn't able to try the things you did as 2/3 of the tank was infested with a terrible hair algae at an epidemic level and had to be thrown out.

Since then I've cut way back on NPK dosing and am pretty much letting the discus feed the tank. I'm still adding small amounts of K along with Ca and Mg in the form of Discus Essential as I've got quite a few Echinodorus in there. So far everyone seems to be doing well.

Kind of tying in to this and the Substrate Fertilization thread, my Walstead tank is going gangbusters! It's by far the best growing of all my setups at the moment. Aside from feeding the fish 3x/day (it's ok Ricky, they're only there as fertilizer factories) the only thing I add is Botanica GH+ for Ca and Mg. There are some Nymphoides spp. lilies in there that are showing color like I've never seen before. The Bacopa and Ludwigia that were in there prior to the redo have recovered really well and are showing lovely growth.

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Regards,
Jay Luto


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## Roger Miller (Jun 19, 2004)

Jay,

Great thread. Thanks. As an historical detail, I think it was actually Steve Dixon in San Francisco that came up with the high potassium doses. Steve's water was very soft. He had the LaMotte potassium kit and ran his tanks up to at least 60 ppm without problems. I understand that other folks in SFBAAPS -- including Tom -- experimented with high potassium levels and reported no problems.

I'm not sure why the San Francisco aquarists didn't have problems. The first and easiest explanation is just that the ones who had potassium-sensitive plants like Nesea either had harder water or they dosed their soft water to higher calcium levels.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## imported_Art_Giacosa (Nov 29, 2003)

My understanding is that potassium excess can lead to problems with magnesium and/or calcium uptake by the plant. Having excess calcium should not resolve a calcium deficiency brought on by a potassium toxicity. The answer, IMO, is to reduce potassium levels so that the toxic states resolves. The plant will then be able to take up calcium normally. This is oftentimes difficult to do as the plants store excess potassium (luxury uptake).

Regards,

Art


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## Roger Miller (Jun 19, 2004)

Hydroponics solutions are commonly made with 200 ppm potassium -- a lot higher than the levels where problems are reported in aquariums -- but that 200 ppm of potassium is balanced by 200 ppm calcium and 50 ppm of magnesium. The problem is caused by unfavorable ratios of potassium to calcium and/or magnesium, not just by high potassium levels. The general guidance is that potassium should never be much higher than calcium (it can be lower) and magnesium should be less than calcium.

It is possible to overcome a potassium problem by adding more calcium, as long as that brings the K:Ca ratio into a more favorable range.

I suspect that potassium and sodium have an additive effect, so it isn't just the ratio of K:Ca that makes the difference, but (K+Na):Ca. A few years back I had problems with calcium deficiency. My tap water carried 7 ppm calcium with 60 ppm sodium and 1 ppm of potassium. That alone didn't cause severe problems. I started adding 10 ppm of potassium to the water changes and suddenly I had a lot of calcium problems. The potassium alone wasn't enough to account for the problems.

For most plants I overcame the problem by putting calcium carbonate tablets in the substrate below the affected plants. That worked for everything but some Ammania senegalensis. There didn't seem to be anything I could do for that plant.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## imported_Art_Giacosa (Nov 29, 2003)

Hey Roger,

I didn't understand your post very well.

I agree that a proper balance should exist between K:Ca and that they are antagonistic elements. To the extent an imbalance of K caused a toxicity in the plant, you can deal with it in a two step approach. First, increasing the antagonistic element (Ca) could interrupt the plants uptake of K and thereby decrease it within the plant. You need to be careful with this as Ca may be antagonistic with other lements.

The preferred approach, in my humble opinion, and what I've always done is to decrease the excess element. This is done via water changes and elimination of K dosing. 

The later corrects the toxicity by bringing K to a more proper balance with Ca and Mg (Mg deficiency is also a symptom of K excess). I think it was you that mentioned, "Don't answer excess with excess."

Regards,

Art


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## Roger Miller (Jun 19, 2004)

> quote:
> 
> I didn't understand your post very well.


Sorry, maybe I can be clearer. Or not.



> quote:
> 
> I agree that a proper balance should exist between K:Ca and that they are antagonistic elements. To the extent an imbalance of K caused a toxicity in the plant, you can deal with it in a two step approach.


Here is one detail that may be confusing. By my reading, the problem with potassium is not a "toxicity." The problem arises when the K:Ca (or K:Mg) ratio in the water column or soil solution is too high. The potassium outside the plant interferes with the plant uptake of calcium. The problem has nothing to do with high potassium concentrations in the plant.



> quote:
> 
> First, increasing the antagonistic element (Ca) could interrupt the plants uptake of K and thereby decrease it within the plant. You need to be careful with this as Ca may be antagonistic with other lements.


In principle I agree. While there is some reason to believe that is true I have yet to come across a case in which it happened. Calcium and magnesiuim concentrations can be -- and often are -- pretty high. Unfortunately, that is the same reasoning that the SFBAAPS folks used to justify very high potassium levels -- they weren't aware of problems.



> quote:
> 
> The preferred approach, in my humble opinion, and what I've always done is to decrease the excess element. This is done via water changes and elimination of K dosing.


I agree completely that if some nutrient is actually in excess then the correct solution is to decrease the dose of that nutrient.



> quote:
> 
> The later corrects the toxicity by bringing K to a more proper balance with Ca and Mg (Mg deficiency is also a symptom of K excess). I think it was you that mentioned, "Don'tnswer excess with excess."


 The catch here is that if the water contains very little calcium or magnesium to start with then potassium can interfere with calcium or magnesium uptake at levels that are not normally considered "excess." In that case, adding a little calcium or magnesium does not create excess calcium or magnesium.

In my case you might say I was balancing excess with excess. My tap water contained an excess of sodium that I could only avoid by using RO or DI water, which I didn't want to do. Adding potassium resulted in calcium deficiency in some plants, but if I didn't add potassium the plants were potassium-deficient. I had to bring potassium, calcium and magnesium up to balance the amount of sodium in my water supply.

Oddly, reducing light and/or CO2 levels is probably another way to offset interference problems. Lower levels of light and CO2 lead to lower growth rates. Under those conditions the plants may be able to get enough calcium and magnesium to satisfy lower growth rates despite unfavorable ratios.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_

[This message was edited by Roger Miller on Tue December 30 2003 at 10:26 AM.]


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## BigFoot (Jan 3, 2005)

is there a pottasium test kit i can buy


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## Rex Grigg (Jan 22, 2004)

Yes, but it's expensive and it's a turbidity test and not that accurate. Potassium doesn't form a lot of colored salts or compounds so the normal color matching test kit just is not available.










American by birth, Marine by the grace of God! This post spell checked with IESpell available at http://www.iespell.com

See my Profile for tank details.

See my planted tank FAQ at http://members.dsl-only.net/~rex/


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## Shane A smith (Jun 15, 2003)

This is an extremely helpful thread. Its definantly helped me understand the subject much better. How could i determine the Mg and calcium level seperatly?

50gal 160watts PC 6500k Clay Substrate.


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## Rex Grigg (Jan 22, 2004)

You can get test kits.










American by birth, Marine by the grace of God! This post spell checked with IESpell available at http://www.iespell.com

See my Profile for tank details.

See my planted tank FAQ at http://members.dsl-only.net/~rex/


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## Shane A smith (Jun 15, 2003)

where do they sell individual calcium/magnesium test kits? Are they expensive?

50gal 160watts PC 6500k Clay Substrate.


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## imported_Art_Giacosa (Nov 29, 2003)

To get an estimate of calcium and magnesium, take your GH number and multiply by .40 for calcium and .24 for magnesium.

Regards,

Art


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## Roger Miller (Jun 19, 2004)

Shane,

I know that Hach sells a hardness test kit that can distinguish between calcium and magnesium. I assume that LaMotte does the same. Either way the kit would be more expensive than any hobby-level test kit.

Art, those conversion factors may not be what is needed. They convert total hardness as ppm CaCO3 to total hardness as calcium or total hardneses as magnesium. That is not the same thing as calculating the calcium or magnesium concentration.

You can probably get information from you water utility about the calcium and magnesium concentrations in your water supply. Otherwise the only way to get those concentrations is to either use a kit that can analyse for them or send a sample to a lab for analysis.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## Guest (Jan 4, 2004)

Continuation.......

*Response from Tom Barr*

I am still skeptical as we worked with softer waters but used only Eustralis. 
It sounds like adding 20-30ppm of K+, plus all the K in SeaChem Eq plus adding the KNO3 is far more than 20ppm or so.

I will say that the plants you have picked are certainly finicky to say the least, I have not worked with Tonia, but have with Ammannia/Nesea/Eustralis. 
Steve had fairly soft tap, he did extrmely well, the best I've seen and over long periods and he added 20-30ppm of K. 
He used SC EQ also and baking soda. 
My water at the time was GH 9. 
My present tap is at 5.

I've had ES rocking with 1/4 teaspoon of K2SO4, 3x a week of KNO3. 
50-70% weekly changes. 
I have not added more than this as far as K+ in many years but I did perhaps 5 and more years ago.

I am certainly more inclined to low tech myself. 
It makes sense but high tech will teach you many good lessons.

Perhaps after a number of years, most, if not all of you will return to that. 
I really like having only two electrical outlets per tank and being able to neglect my tanks if I want.

I think folks are thinking what I often suggest is something far different than what Luis or others maybe be doing. I would even say much of what I do can certainly be scaled back and are that different, the plants certainly are not limited with the higher dosing methods, but as you get to know your tanks, plants etc, you can tweak things to your routine and run a "lean" tank. Many folks have done this in sfbappas. Most were conservative believe PO4 and other nutrients caused algae. 
Soem tried higher dosing, some stuck with the lower dosages.

I told Steve that we could likely add nothing but KNO3 alone to supply the K+, but I have dose /K2SO4 along with for many years. I just never saw what folks are saying, maybe you guys have something other than K2SO4 in there. 
40-50ppm, it was many of us, no one had issues for years till after some one said K+ blocks Ca++ which is plain hogwash. Divalents and monovalent transporter are not remotely similar, and Ca, K interactions for inhibition are related to Stomal controls feedback loops in , not nutrient uptake.

I have had no troubles with Eustralis BTW, I have softer water now and it gets all big and nice with excellent colors. 
I have suspected but am reluctant to point the finger that hardness has something to do with it at higher light levels, but at lower levels, it does better in harder water.

It also seems to like a good source of NH4 via fish waste and did well with high and low PO4.

One thing to consider, adding the levels I often suggest is more than enough to fatten up any plants well, but you can certainly micro manange and dose little spikes here and there which will give you more than enough to make it for a while till the next time.

Sort of like eating a meal that keeps you full but dose not bloat you. 
But if you are having algae issues, it's not from the excess for the plants etc, you are not balancing something correctly.

Slowing down something through limitation wil often correct some mild limitations.

Well gotta sleep, I'll post again about the substrate, my suggestions for the substrate is not far off from Luis's, I don't add tabs, but I use peat, mulm extensively. Both of which make a substrate rich/fertile etc, unless you are adding jobes, etc, NO3, PO4 etc, it's not that rich really.

Eco complete is a decent substrate, much like Amano's, sort of a toughened up mulm. I've used the stuff twice now and used Amano's.

*Response from Ghazanfar*
In agriculture, excess K does inhbit Ca uptake - atleast from what I've read. However, with aquatic plants, maybe the ratio of K : Ca 
plays a role? Hard water / softwater(with no Ca additions) may yeild different results with high K?

*Response from Tom Barr*
I think there may be some plant specific issues with finicky plants. 
But overall for most plants, K+ has not seemed to cause issues. 
Paul, myself, Neil, most of the folks in sfbapps, the APD, went nuts with K+.

But I also known that ES has been a funny plant with harder waters at least for me, I know on one person that did well at a KH of 8, I do not know what the Gh was though or the Ca++ levels. 
I have about 5GH now and the plant goes nuts at higher K+ (20ppm or so). 
I got it to grow and look nice with some work in harder waters, but not the size, but did get good color. 
In soft water, I have no issues with either. It's a weed.

But in terms of plant specific needs, there are very likely plants that will do better with less K+, or more PO4 or more NO3, less Fe etc 
Noting these is a good idea but saying causation is tough to say the least.

I'm leary about that.

What was the reference you found for the K+/Ca thing also? I think I read it in the past but I want to take another look.

*Response from Ghazanfar*
From what I remember, it was something along the lines that plants will take in K even though they may not need it. With elevated levels of K, they will increase their uptake of K which will retard the uptake of Ca. Now to figure out where I read the damned thing...

*Response from Tom Barr*
This is a repost:

If you dose a fair amount of NO3 via KNO3, keep nice tank parameters, don't have lots of Bait, I'd suspect you don't need to add K separately.

Steve and I did this for awhile, there were times when folks could not get any K2SO4 around the area, so we did without.

We never really found much difference.

If you are 6.4 ppm of so of NO3, then you add 4 ppm of K using KNO3. Some products have K+, like TMG. 
I find it unlikely you really need MORE K+ to grow plants well and ************it's one less thing that folks need to dose which is my goal here****. 
Looking at a mass balance of N/K+ ratios, **most** plants have about 1.5/1 ratios of N to K(Epstien 1972).

Now take into account the O3 part of NO3 and to get N and you suddenly find you have plenty of K+ for plant growth. 
So 1.5/4.4= .34 N's for every K+ you add.

So you should theoretically have 3x as much K as you need relative to N. 
There are other sources of N, plant decomposition, fish waste but some K+ comes from these pools also.

Unlike NO3 and denitrifying bacteria NO3=>N2 gas, there is not much to the K+ cycle except for plant uptake/leaching.

So it certainly is something folks can skip if they add KNO3 as their main source of N.

Now if you have a good fish load, over feed Discus, slow growth/non CO2 etc, adding K+ from KCl/K2SO4 is advisable since you already will have plenty of NO3.

But for many, KNO3 as the source of both N and K should do the trick.

How about them apples?

I'd say you simply don't need but 3 things, KH2PO4, KNO3 and traces. 
And then the other two parts: Light and CO2.

I'm glad Ghori brought it up as I've not thought about it since I guess 1997 or so. But going through it, it should not be a problem even with all the different plant species needs and possible extra K+ needs a plant might have.

I think it's be EVEN easier for the new folks and us too, to delete one more nutrient from the mix.

That is a GOOD GOAL.

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Regards,
Jay Luto


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## Roger Miller (Jun 19, 2004)

The potassium thread is starting to annoy me. Virtually every source I read about fertilizing with potassium cautions about maintaining correct proportions between potassium, calcium and magnesium.

This isn't new science. It isn't rocket science.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## Guest (Jan 5, 2004)

> quote:
> 
> Originally posted by Roger Miller:
> The potassium thread is starting to annoy me


Really ????









I think idea behind this post is to inform new people about "new" possibilities or ways to maintain fertilizer schedule, most important eliminating Potassium addition <-- general statement.

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Regards,
Jay Luto


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## anonapersona (Mar 11, 2004)

> quote:
> 
> Originally posted by Roger Miller:
> The potassium thread is starting to annoy me. Virtually every source I read about fertilizing with potassium cautions about maintaining correct proportions between potassium, calcium and magnesium.


So, maybe the addition of K depends more on the GH of the water?


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## Roger Miller (Jun 19, 2004)

> quote:
> 
> Originally posted by anonapersona:
> So, maybe the addition of K depends more on the GH of the water?


For many aquariums potassium should depend on the GH of the water. There are a lot of other variables as well.

When Tom and the SFBAAPS folks came up with the 20 ppm recommendation it was based on the belief that there were no problems with dosing potassium. 20 ppm was a conservative answer to the question "How much can we dose." It did not answer the question "How much do we need to dose." We should assume that there is a downside and some cost to everything we add to our aquariums. We have to provide our plants with everything they need to grow on. Ideally we would give them no more than they need to grow on.

This sort of argument is not unique to aquariums. In summer, '02 I spent a couple days touring some midwest farm lands with an agricultural engineer. The farm programs he worked with were at the same point. He thought the farmers were just starting to learn how to provide crops with what they needed without providing more than was beneficial or more than would be potentially damaging.

For farmers the balancing act is a matter of increased cost vs increased production. For aquarium keepers the costs are generally low and the production has little or no monetary value, so economics are rarely a factor. Instead we have to balance time and labor and the health of our aquariums against the needs for healthy growth of plants. We don't understand many of the factors involved so our best approach is the conservative approach.

So now with Tom's most recent suggestion we can jump on another bandwagon; the original sfbaaps method was the new method that replaced the old new method, so this must be the new, new method. It's a parade!

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## imported_Art_Giacosa (Nov 29, 2003)

Well said.

Regards,

Art


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## anonapersona (Mar 11, 2004)

> quote:
> 
> Originally posted by Roger Miller:
> 
> So now with Tom's most recent suggestion we can jump on another bandwagon; the original sfbaaps method was the new method that replaced the old new method, so this must be the new, new method. It's a parade!


LOL
Well, you know that we are mostly a bunch of techies of one sort or another, always trying to discover the BEST way to do something. If its good we want it better... faster, cheaper, more automated, some sort of improvement MUST be possible. Anything else would be boring.


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## Ptahkeem (Feb 16, 2004)

This thread is confusing me. Im no whiz with plant fertilizing and such. I have checked out my local water sources and the levels I have in my tap are as follows:
Ca 59.8ppm
Mg 20.5ppm
K 4.16ppm
So according to these numbers my Ca:K ratio isnt 4:1. I dont dose with KNO3 or KPO4 instead I use the seachem line currently. Should I be dosing K to get the 4:1 Ca:K ratio? Please help as Im lost in this very detailed discussion. Thanks =)


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## Planted Engineer (Jan 15, 2004)

Hi,

I tried looking for a calcium test kit today and found out that Sera, Red-sea and Aquarium Supply are all reef/marine/salt water oriented. Can I still use them? If not - which test kit is recommended? Ofcourse the LFS seller have never met a guy trying to test for calcium in a fresh water tank... ;-)

I am trying to get this calcium test kit because since I started dosing potassium (5 tsp per 190 gallon) the hygro polysperma new leaves edges became white and crinkled. BTW the old plysperma's growth is still not recovered - this is why I was wondering if I need to dose *more*postassium... but now after reading this - I am even more confused.

PE.


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## Roger Miller (Jun 19, 2004)

You don't have to worry about maintaining a 4:1 Ca:K ratio in your water. Such a specific ratio would occur only rarely in nature, so absolutely nothing has evolved to require it.

The value of this thread my be completely outweighed by the confusion it can cause.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## vinz (Feb 19, 2004)

From what I've read, you can use the calcium test kits for FW too. Get one that has a good resolution... ie. one that can measure Ca at smaller intervals. Most I've checked measure Ca at 20ppm steps. If you can find one that does it at 4 or 5 ppm steps, its better.

1ppm of Ca accounts for about 0.14 dGH
1ppm of Mg accounts for about 0.23 dGH

Vincent
Home: Aquatic Habitats Hangout: Aquatic Quotient


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## Yuschka (Nov 8, 2004)

Some of you may be interested in how much Mr Amano is dosing potassium. I ordered a few months ago a bottle of ADA's potassium supplement "Brighty K", which in fact is a solution of potassiumbicarbonate plus something to neutralise chlorine. ADA recommends that Brighty K is added to tap water at every water change. The recommended dosage gives a potassium level of about 25 mg K+ per litre (plus K+ naturally in the tap water). Additionally, Brighty K is dosed daily to add 2.5 mg K+ per litre.

Since Brighty K contains bicarbonates, its use increases KH (carbonate hardness). The recommended dosage at water change raises KH by one German degree. Daily dosage increases KH about 0.5 German degree per week. Consequently, KH is almost always similar to or higher than GH (general hardness) in Mr Amano's tanks (see, for instance, the data in his books "Nature Aquarium World, book 2" and "Aquarium Plant Paradise). It is interesting to note that David Wilson wrote in his article in "The Aquatic Gardener" (vol. 15, No. 1, pages 30 – 35): "One observation that may be of interest to water plant growers is the creeks and rivers with best natural submerged plant growth had carbonate hardness readings similar to the hardness readings". I think the components of Brighty K suggests that Mr Amano has noticed the same.

Finally, I would like to point out that all the potassium measurements were made with The Aquarium Landscapes' potassium kit. To measure high potassium concentrations with said kit requires sample diluting. Thus, my results may not be as exact as they could be. However, I believe that the results are surely indicative.

"If the desired tank seems too expensive, settle for a cheaper one" - Takashi Amano


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## Freemann (Mar 19, 2004)

Corrected it. Here is a long article on magnesium and some good ways to measure it.
http://web.archive.org/web/20030624222658/http://www.animalnetwork.com/fish2/aqfm/1999/mar/bio/default.asp

[This message was edited by Freeman on Fri February 13 2004 at 11:49 AM.]


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## vinz (Feb 19, 2004)

Freeman,

Your link does not work for me, but I searched around in AnimalNetwork.com and found http://www.aquariumfish.com/aquariumfish/detail.aspx?aid=2345&cid=124&search=

Is this the correct article?

Vincent
Home: Aquatic Habitats Hangout: Aquatic Quotient


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## skunky (Jun 22, 2003)

Being a 'fish keeper' more so than an aquatic gardener, one thing that does concern me is that by adding around 1 tsp of potassium sulfate will lead to an increase in GH by up to 50ppm. Times this by twice a week and you have an increase of around 6 degrees GH. Great for plants maybe, not fantastic news for the more sensitive species, especially wild caught fish such as Discus from softer waters!

Just a thought.


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## Roger Miller (Jun 19, 2004)

Adding potassium sulfate doesn't change the GH. It doesn't change the KH either. It will increase the dissolved solids and electrical conductivity.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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## skunky (Jun 22, 2003)

So, I'm a little confused!

Explain to me the difference between TDS and GH. I was under the impression that if you divided the TDS in ppm by 17.9, then this would give you degrees of general hardness?


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## Roger Miller (Jun 19, 2004)

If you divide general hardness in ppm by 17.9 then you will get the degrees of general hardness. TDS stands for "total dissolved solids" and the name means exactly what it sounds like. TDS is a measure of *everything* (almost) dissolved in the water. Hardness measures only the magnesium and calcium.

Roger Miller

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_"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein_


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