# [Wet Thumb Forum]-What happens to the Cl ions in KCl?



## GulfCoastAquarian (Feb 3, 2003)

Although I am familiar with chemistry principles, I am not experienced with the biology of how plants react with them.

My question is, after plants utilize the potassium in Potassium Chloride, what happens to the Chloride ions? Is there a chance they bind with Calcium in the water? Ever since I started dosing KCl, my Sunset Hygro (and a few other plants) seem to be showing what might be a Ca deficiency (shriveled, weak new leaves).

I might be way off in my assumptions here, so I thought I'd just ask the question and see what really happens.

Thanks!

-Sam P, BSME
My Website


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## GulfCoastAquarian (Feb 3, 2003)

Although I am familiar with chemistry principles, I am not experienced with the biology of how plants react with them.

My question is, after plants utilize the potassium in Potassium Chloride, what happens to the Chloride ions? Is there a chance they bind with Calcium in the water? Ever since I started dosing KCl, my Sunset Hygro (and a few other plants) seem to be showing what might be a Ca deficiency (shriveled, weak new leaves).

I might be way off in my assumptions here, so I thought I'd just ask the question and see what really happens.

Thanks!

-Sam P, BSME
My Website


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## Roger Miller (Jun 19, 2004)

Chloride remains in the water. It doesn't bind with anything unless the concentrations become very high -- like sea water. Even then, chloride forms only weak associations.

What is your hardness? Can you get an analysis of your water supply from the utility? How much KCl are you dosing? Are you adding bicarb?

So many questions...

Roger Miller


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## GulfCoastAquarian (Feb 3, 2003)

Thanks for the answer to my first question!

My carbonate hardness is around 6-7 dKH (RedSea test), I don't know my general hardness. I got a water analysis of my tap water recently in the mail but can't find it now. What specifically are you looking for?
I am dosing about 1 to 1 1/2 tsp of KCl a week. Not adding any bicarb.

Thanks again!

-Sam P, BSME
My Website


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## Roger Miller (Jun 19, 2004)

I was looking for general (or total) hardness, sodium concentration, boron concentration and anything else that might give a clue to the distorted growth. Can we eliminate the possibility that you are using a water softener?

Roger Miller


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## anonapersona (Mar 11, 2004)

Just wanted to note that I'm following the discussion closely, as GulfCoast and I have similar water and since I've gone back to adding KCl I'm seeing white deposits on the top of the driftwood and filter return again. It had gone away while I had stopped KCl. I'm aso seeing pale growth and ragged leaves on some vals and on Apong. Ulvaceus. 

Is there any chance that the KCl is acting like a water softener would, taking out Calcium and dropping it as a precipitate?


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## Roger Miller (Jun 19, 2004)

> quote:
> 
> Is there any chance that the KCl is acting like a water softener would, taking out Calcium and dropping it as a precipitate?


Nope. Could there be a lot of impurities in your KCl?

Roger Miller


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## kor4ever (Mar 22, 2003)

Correct me if I'm wrong, but don't plants uptake chloride ions for osmotic balance purposes?

I've taken too much organic chemistry and forgotten all my general chem. I agree with Roger that the Ca could not drop out of solution, however, if you dose potassium sulfate, its possible that the addition of KCl will cause the precipitation of calcium sulfate.

I mean, if you have the following equation
1)
CaSO4(s)<->Ca(aq)+SO4(aq)

2)
K2SO4<-> 2K(aq)+SO4(aq)

So according to LeChatelier's Principle, if you add stress to one side of the equilibrium, it will push the equilibrium to the opposite side. However, since all elements in the first column are perfectly soluble, the only way to remove the stress on the right side of the second equation when you add KCl(addition of potassium ions)is to remove the amount of SO4 ions. Thus the equilibrium on the first equation should move to the left and CaSO4 has limited solubility.

However, all conjecture, feel free to correct me if I am wrong.

Felix

20G heavily planted tank with natural gravel and a layer of black sand on top. 
DIY C02, Emperor 280 filter(also my CO2 reactor), 4 18' fluorescent tubes(2 Philips P&A, Philips Natural Color, and 1 GE Aquarays).

[This message was edited by kor4ever on Mon March 31 2003 at 09:07 AM.]


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## GulfCoastAquarian (Feb 3, 2003)

Not using water softener. There are a great deal of impurities in my KCl as far as plants are concerned since this is a table salt subsitute (NoSalt). Sever other board members have used this same brand without difficulties, though. That is not to say some of these extra ingredients aren't possible reacting with my particular water chemistry.
Here are the listed ingredients for my KCl source:


Potassium chloride
Potassium bitartrate
Adipic Acid
Fumaric Acid
Silicon Dioxide
Mineral Oil

I did find some tap water analysis from a report a few years back and it listed Copper as 0.130-0.150 ppm. Lead is 3-4 ppb. Not sure if that helps, though. Sorry.

-Sam P, BSME
My Website


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## kor4ever (Mar 22, 2003)

Not sure if you said Sam, do you dose potassium sulfate? 

Copper and Lead wouldn't lead to precipitation of calcium, defintely not at that concentration.

Felix

20G heavily planted tank with natural gravel and a layer of black sand on top. 
DIY C02, Emperor 280 filter(also my CO2 reactor), 4 18' fluorescent tubes(2 Philips P&A, Philips Natural Color, and 1 GE Aquarays).


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## Roger Miller (Jun 19, 2004)

> quote:
> 
> Originally posted by kor4ever:
> Correct me if I'm wrong, but don't plants uptake chloride ions for osmotic balance purposes?


I think they do. Some chloride is essential, but they don't use it at anything like the 1:1 molar ratio in KCl, so some Cl- will be "left over."



> quote:
> 
> I've taken too much organic chemistry and forgotten all my general chem. I agree with Roger that the Ca could not drop out of solution, however, if you dose potassium sulfate, its possible that the addition of KCl will cause the precipitation of calcium sulfate.


Calcium sulfate is far too soluble to precipitate from fresh water.

Roger Miller


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## kor4ever (Mar 22, 2003)

> quote:
> 
> Calcium sulfate is far too soluble to precipitate from fresh water.


Calcium sulfate is not highly soluble like KCL or NaCl is, it is not as insoluble as ferric sulfate is either. It is slightly soluble in water, I'll check on the specific number later. But all sulfates are soluble except Ba, Ca, Pb. Plus CaSO4 is less soluble at higher temperature according to this website

http://www.platingprocess.com/calcium.htm

Felix

20G heavily planted tank with natural gravel and a layer of black sand on top. 
DIY C02, Emperor 280 filter(also my CO2 reactor), 4 18' fluorescent tubes(2 Philips P&A, Philips Natural Color, and 1 GE Aquarays).


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## Antonio Trías (Feb 4, 2004)

I think if is an excess of k in the water will produce Ca deficiency in plants. Nothing about Ca precipitation

Best Regards
Antonio TrÃ­as


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## kor4ever (Mar 22, 2003)

Could be, just trying to account for the precipitation Anona noticed in his tank.

Felix

20G heavily planted tank with natural gravel and a layer of black sand on top. 
DIY C02, Emperor 280 filter(also my CO2 reactor), 4 18' fluorescent tubes(2 Philips P&A, Philips Natural Color, and 1 GE Aquarays).


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## Roger Miller (Jun 19, 2004)

> quote:
> 
> Originally posted by kor4ever:
> Calcium sulfate is not highly soluble like KCL or NaCl is


That's right, but it still won't precipitate from fresh water at normal temperatures.

The solubility product for CaSO4 (I presume this is the dihydrate, because the other forms don't precipitate from solution) is 2.45x10^-5 in molar units. If calcium and sulfate were present in equal molar amounts, then precipitation would require them to be present at concentrations higher than 198 mg/l for calcium and 475 mg/l for sulfate.

The 198 mg/l of calcium is feasible. That would be 247.5 ppm hardness, or about 14 dGH hardness. The sulfate concentration is unlikely. The common drinking water standard is 250 mg/l, so 475 mg/l of sulfate is nearly double that amount.

Of course, calcium and sulfate don't have to be in equal amounts. If sulfate were at the drinking water limit of 250 mg/l then the calcium concentration would have to exceed 376 mg/l to get calcium sulfate to precipitate. That's 470 ppm of hardness or about 26 dGH of hardness.

Calcium and sulfate concentrations would have to far exceed these "equilibrium" values before precipitation would occur at a noticable rate. In nature calcium carbonate usually precipitates long before calcium sulfate.

Roger Miller


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## GulfCoastAquarian (Feb 3, 2003)

> quote:
> 
> Originally posted by kor4ever:
> Not sure if you said Sam, do you dose potassium sulfate?


No, never have. Only K sources I've used have been Flourish Potassium and KCl in the form of "NoSalt". I used to dose Magnesium Sulfate occasionally but have since ceased that supplement.

-Sam P, BSME
My Website


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## Roger Miller (Jun 19, 2004)

> quote:
> 
> other board members have used this same brand without difficulties, though. That is not to say some of these extra ingredients aren't possible reacting with my particular water chemistry.
> Here are the listed ingredients for my KCl source:
> ...


I've used a nosalt suppliment for potassium -- something similar if not identical. Based on the label I concluded that the stuff is at least 96% KCl. I looked up the remaining ingredients and found them to be harmless. The silicon dioxide may not be insoluble and that might produce some cloudiness.

Anona, are you using a NoSalt suppliment too? I guess the white stuff you're seeing could be silicon dioxide settling out. I never saw anything like that while I was using it, but I never added it directly to my aquarium. I always mixed suppliments along with dechlorinator in a large garbage can, then used water from the garbage can for my water changes.

Roger Miller


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## wetmanNY (Feb 1, 2003)

Imbalances of competitive macronutrients may manifest themselves in symptoms that are virtually indistinguishable from deficiencies. Since Ca, Mg and K compete for uptake sites in plants, a superfluity of Mg or K can register as if it were a calcium deficiency.

No precipitation would be required.

Calcium is immobile, I've recently been reminded, and doesn't translocate from mature to new growth. So new growth is especially vulnerable to symptoms of calcium "deficiency."

My sources are all concerned with nutrient uptake in terrestrial agriculture, so they may be dismissed as inapplicable to water plants.


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## Guest (Mar 31, 2003)

Why not try the K2SO4 and see if it works better than the KCL?

I've heard a number of odd things about KCl but many also have had no issues with it. This likely means that something else is causing the issue and not the KCl. But a combo of very soft/very hard tap water in conjuction with KCl might cause an issue. I just stick with the K2SO4. I know it does not do anything I cannot account for.
I use a fine powdered K2SO4. Stuff dissolves very fast(seconds to a minute).

The SeaChem K+ is KCl. 

Cl is required for the water splitting at the start of PSII, cell division also. 

Regards, 
Tom Barr


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## anonapersona (Mar 11, 2004)

> quote:
> 
> Originally posted by Roger Miller:
> Anona, are you using a NoSalt suppliment too? I guess the white stuff you're seeing could be silicon dioxide settling out. I never saw anything like that while I was using it, but I never added it directly to my aquarium.
> ...


I am using KCl water softener pellets, added to distilled water to make a totally clear solution that adds 3 ppm to my tank per ml dosed. The pellets are large white chunks, vaguely chrystaline with a bit of glitter to them, each about 1" or less by 3/8"x 1/4". As large as they are, I dissolve 0.7 oz per 100 ml of water which is maybe 5 chunks of various sizes (about equal to my finger), with about 5 minutes of shaking using room temp water. Pretty easy to dissolve given the size of the chunks.

I also saw this precipitate when I was using Murate of Potash, it says it is "soluble potash K2O 60% and chlorine not more than 46.7%". I stopped using it when I began losing the panda cories, 4 out of 5 died of unknown causes. That made a opaque pink solution which I thought might be involved in the strange stupor and loss of equlibrium. The 4th one died after the KCl was halted, but after a major tank rearrangement.

After awhile, most of the deposits that was on the driftwood went away or was covered in algae, I can't quite recall. The deposits on the filter tube which were crusty and had come back after being cleaned off while I was using K suppliments, never returned after I quit the KCl. This did return within a few weeks of resuming with the KCl.

Maybe I am just using too much. Is there a ratio of NO3 to K that I could follow? My tank is not high light (just under 2wpg) and I add only 7 ppm of KNO3 during a week to keep NO3 at 10 ppm by the end of the week. I've been adding 21 ppm of KCl per week. Maybe the 3:1 ratio is incorrect?


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