# Potassium Bicarbonate



## Salt

Has anyone had any experience using Potassium Bicarbonate to raise KH rather than baking soda. Does it dissolve quickly?

I'm wondering if this isn't a better alternative than Sodium Bicarbonate (baking soda) so as to avoid adding a lot of sodium to the tank, or at least replace the sodium with a real macronutrient plants can use.

Seachem says Alkaline Buffer has some in it, but they also say it's a "sodium bicarbonate based buffer."

It should be available from some lab suppliers. Wondering if anyone has had any experience with it.


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## titan97

A quick search turns up that KHCO3 is soluble to 36g in 100g of water, and NaHCO3 is soluble to 10g in 100g of water. Taking into consideration the different mass weights of Na and K, KHCO3 would appear to be MORE soluble than the NaHCO3. This would leave me to believe that KHCO3 should work just fine as a substitute for NaHCO3. Finding it as readily as baking soda is another question. Perhaps, if there were enough interest, we could ask Greg Watson to carry this product. I'd imagine it would be just as cheap as the other dry ferts he carries.

-Dustin


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## BryceM

I know that there are people out there using it. 1 tsp of NaHCO3 in 10 gallons of water adds about 30 ppm Na. I don't know if that's a ton, but it doesn't seem insignificant.


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## dennis

I have some K2CO3, or potassium carbonate I got from a friend in a lab. It is pretty cheap considering how long it would last, the only problem is the amount of K added. I do not have the calculations anymore, however I believe the post here explains it...
http://www.aquaticplantcentral.com/forumapc/showthread.php?t=8348

Basically using K2CO3 you add 22mg/l K for every 1 degree of hardness added by the CO3. That is quite a bit of K considering we already add enough, usually, through KNO3 and KH2PO4. IF you use any Seachem Equibrilirium you are adding a ton more K.

KHCO3 should add less K for every degree of hardness but still, I wonder how much is too much? I know I have had some wierd things happen when I add more than normal K amounts. Might have been my imigination or another factor I was un aware of though.....


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## Salt

Potassium Bicarbonate is looking better and better... Potassium and Calcium have very close atomic weights, so it's very similar to Calcium Carbonate which is the standard for degrees of hardness. I just did some calculations, and I'm showing that you can dose Potassium Bicarbonate to raise both KH and K without a need to dose Potassium Sulfate and Sodium Bicarbonate separetely:

Let's start with degrees of hardness. The standard is 1 degree of hardness is equal to exactly 10 ppm of Calcium Oxide (CaO).

Ca = 40.078 moles
O = 15.9994 moles

CaO = 56.0774 moles

10 ppm CaO = 1 dGH

71.46908 % Calcium
28.53092 % Oxygen

1 dGH contains

7.146908 ppm Ca
2.853092 ppm O

Now carbonate has no calcium, so we must use a standard of calcium carbonate to get degrees of hardness for carbonates.

CaCO3 = 100.0869 moles

40.04320 % Calcium
59.95680 % Carbonate

X * .4004320 = 7.146908 ppm calcium
X = 17.84799 ppm Calcium Carbonate in 1 dKH
17.84799 * .5995680 = 10.70109 ppm Carbonate in 1 dKH

Now that we know how much ppm of carbonate 1 degree contains, we move on to potassium bicarbonate - KHCO3.

K = 39.0983 moles
H = 1.00794 moles
CO3 = 60.0089 moles

KHCO3 = 100.11514 moles

1 / (60.0089 / 100.11514) = 1.668338 mg to raise CO3 1 ppm in 1 liter
17.853037 mg to raise CO3 10.70109 ppm (1 dKH) in 1 liter (note this is nearly equal to calcium carbonte)
67.581101 mg to raise CO3 10.70109 ppm (1 dKH) in 1 gallon

Potassium - 1 ppm in 1 liter:

1 / (39.0983 / 100.11514) = 2.560601 mg to raise K 1 ppm in 1 liter
1.668338 mg / 2.560601 mg = 0.651542 ppm K increase for every 1 ppm of carbonate increase

Example - Raise RO/DI water 5 dKH with Potassium Bicarbonate:

5 dKH = 34.8610479039 ppm Potassium

Not looking bad at all.


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## dennis

Not to bad but if you follow EI, or something similar and dose 10ppmNO3 and .5ppm PO4 4x week you are adding about 28ppm K. Now you are up to 62ppmK a week. If you are also are reising the Gh using Equibrilium, you are adding probably as much again K as I know Equilibrium adds alot of K. All this means you may be adding 100+ppm K weekly...

Not sure what that will hurt, if anything, just a heads up


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## BryceM

In the long run it's probably best to stick with CaCO3. The calcium isn't going to hurt anything except raising the GH, which probably needs to go up anyway if you're trying to fix a low KH. Too bad it is so insoluble. I haven't tried Greg Watson's CaCO3 -- does anyone know how finely powdered it is? My only reason for sticking with baking soda is that with a large WC (per EI) it's nice to quickly get the KH where you want it. I'm told (and it seems to make sense) that finely powdered CaCO3 will dissolve in a few hours.

From a viewpoint of physiology, high K levels will eventually make a difference. I could tell you what high levels do to humans, but fish physiology isn't a bit more mysterious. It's an easy enough experiment to do if someone is bored and/or interested.


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## Raul-7

> The calcium isn't going to hurt anything except raising the GH, which probably needs to go up anyway if you're trying to fix a low KH.


But kH and gH are not related in any way at all.

As for the potassium carbonate, it might be a great solution if your using the KHCO3, as your sole source of K for the aquarium. But given the fact that most people use KNO3. I think you would risk an overdose. Doesn't high K levels limit Ca uptake? Are there any other useful methods of increasing kH without introducing unwanted elements?


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## Salt

How about some more alternative chemicals? 

You could dose ammonium nitrate - NH4NO3 - instead of potassium nitrate. I'll bet plants would respond much better to it. Ammonium (NH4+) is much closer in structure to an amine group (NH2) which is used to make plant proteins than Nitrate (NO3). Because of that plants are able to utilize ammonia and ammonium more easily than NO3. Seachem Nitrogen is said to be half ammonium and half nitrate... so is ammonium nitrate. 

You could also use mono ammonium phosphate - NH4H2PO4.

There are places to buy these for decent prices. For example, ebay:

Ammonium Phosphate - http://cgi.ebay.com/Ammonium-phosph...ryZ26420QQssPageNameZWD1VQQrdZ1QQcmdZViewItem

Or Chemsavers:

Ammonium Nitrate - http://www.chemsavers.com/index.cfm?fuseaction=detail&id=12634&product=1472

There's also Clarksonlab.com, and ScienceLab.com (which starts getting away from wholesale prices however).

When dosing Ammonium Nitrate, go for 5 ppm nitrate instead of 10 ppm since the other half (or so) of the nitrogen is coming from Ammonium.


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## BryceM

Raul-7 said:


> But kH and gH are not related in any way at all.


They are when you're using CaCO3. The carbonate dissolves and increases KH and the Ca increases GH. Most buffering capacity in nature comes from limestone (CaCO3) that dissolves into the water on its way to your faucet. This is why almost all natural water sources contain either high KH & GH or low KH & GH (hard & alkaline vs. soft & acidic).


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## BryceM

Salt said:


> How about some more alternative chemicals?
> 
> You could dose ammonium nitrate - NH4NO3 - instead of potassium nitrate. I'll bet plants would respond much better to it. Ammonium (NH4+) is much closer in structure to an amine group (NH2) which is used to make plant proteins than Nitrate (NO3). Because of that plants are able to utilize ammonia and ammonium more easily than NO3. Seachem Nitrogen is said to be half ammonium and half nitrate... so is ammonium nitrate.


Supposedly (per Tom Barr) the direct addition of NH4+ will indeed boost plant growth but will also result in a most impressive algae bloom. I've never tried it myself, but if that's what he says, it's good enough for me. I'm already doing a good enough job at algae growing.


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## Salt

I don't buy that.. I've used Seachem Nitrogen and have never experienced an algae bloom. Seachem Nitrogen has ammonium in it.


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## dennis

seachem website said:


> Flourish Nitrogen™ is a concentrated (15,000 mg/L) blend of nitrogen sources. It provides nitrogen in both the nitrate form and the plant-preferred ammonium form. However, no free ammonia is released because the ammonium in Flourish Nitrogen™ is complexed and unavailable until utilized by the plants.


I don't believe your NH4NO3 complexed as Seachem's is. If it is not, you will have a very green aquarium adding this stuff, green glass, rocks, wood and plants

If you still want to add NO3 and Ca, use CaNO3 (or is it Ca2NO3?) If memory serves that is reportedly very soluable and will add source of Ca and NO3

If you are really worried about your CaCO3 not dissolving, mix it up before hand, or use tablets thrown into the filter. You could also probably mix it in solution with a weak acid to dissolve the powder before adding it to the aquarium.

As for K levels affecting Ca uptake...Tom Barr swears up and down it will not, although I do not know if his swearing counts at K levels 100+.


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## Salt

Seachem's basic dosing instructions for Flourish Nitrogen is 1 ppm twice per week. I'd bet if you calculated and dosed only a few ppm of NH4NO3, you wouldn't get an algae bloom.


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## dennis

What good would dosing only a few ppm do, and are you basing that on an NH4 or a NO3 dose. If you are only going to dose a few ppm, might as well jsut feed the fish more, or add more fish.

Aside from that, I bet it would induce an algae bloom. Even a sudden ammonia spike of 1ppm can induce algae outbreaks in the aquarium. Remember, algae do not necesarily live in the same enviroment as the plants/fish. Algae can utilize nutrients, especially NH3/4 in the ppb levels. The bind between the NO3 and the NH4 would probably dissociate very easily, making it readily available to both plants and algae.

Plants and algae both use NH4/NO3 from the same source first, the water column, however algae get a much stronger bonus for 2 reasons. First, their ability to utilize much lower levels, in the ppb range, compared to plants means that algae essentially get "first dibs" at the nutrient. Second, and more importantly, through evolutionary conditioning (not sure if that is a real term but it seems to fit here) algae has adapted to recognize sudden increases in NH3/4 as preferable growth conditions, causing a rapid growth/bloom...much like a sudden desert rain triggers plants in that ecosystem to flower, seed and sprout.

It would be great though to find I am completely wrong that that this is an excellent fertilizing method. All the above is based on logic, interpretation and a basic understanding of chemistry and plant physiology and is by no means an scientific statement...


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## Salt

Well, the truth is neither of us has tried or tested it. If I can get ahold of some I might experiment (and will report the results). 

As I said, Seachem advises dosing 2 ppm of their nitrogen product a week as a beginning dose.


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## BryceM

Ask Tom Barr. He's tried it. Its in the opening paragraphs of his EI article. He reports massive algae blooms with NH4 - like I said before, good enough for me.


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## RuslanJamil

dennis said:


> If you still want to add NO3 and Ca, use CaNO3 (or is it Ca2NO3?) If memory serves that is reportedly very soluable and will add source of Ca and NO3


I use Calcium Nitrate Ca(NO3)2 to dose calcium and nitrogen and yes, it is very soluble.


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## Salt

guaiac_boy said:


> Ask Tom Barr. He's tried it. Its in the opening paragraphs of his EI article. He reports massive algae blooms with NH4 - like I said before, good enough for me.


But did he dose Ammonium Nitrate, and if so, how much?


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## dennis

Salt said:


> Well, the truth is neither of us has tried or tested it. If I can get ahold of some I might experiment (and will report the results).
> 
> As I said, Seachem advises dosing 2 ppm of their nitrogen product a week as a beginning dose.


You are absolutely correct. As I said, I speak with only anecdotal evidence and basic logic. I know this is something I will have to overcome if I plan to work in a field of science;however, I like to try and figure out the answers to questions before I experiment just to see if I was right

What are the parameters of the tank you want to try this on? If you are dosing 2ppm of N (again what form of N is this dose based on, I am assuming they consider it total N, derived from all N forms), you are not doseing enough unless you have a low light, no-CO2 setup. If you have even moderate light, with or without CO2, you rdeficient N levels will only compound the issues regarding NH4 addition.

A quick search finds that Seachem Nitrogen is derived from KNO3 and Urea, (NH2)2CO or CON2H4. See here I remember comments about urea in the aquarium from past APD discussions, however I don't remember the outcomes of those discussions... Chemistry was a long time ago so does anybody care to do the formula for mixing urea + H2O?

Just food for thought...


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## Salt

Also...

Raising nitrate by 10 ppm using KNO3 only raises potassium by 6 ppm.

Raising nitrate by 10 ppm using Ca(NO3)2*4H2O (Calcium Nitrate Tetrahydrate) will raise calcium by 3.23 ppm. (7.15 ppm calcium = 1 dGH)

According to the Seachem MSDS, Flourish Nitrogen contains guanidine as the complexed ammonium source.


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## Raul-7

Sorry to bring this back, but I just had a discussion with Seachem Tech Support and he claims that nitrogen in water of a pH 7 or below will be converted into the ammonium form, while above 7 it will be converted into ammonia. Do you think this is logical?


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## RTR

http://bridge.ecn.purdue.edu/~piwc/w3-research/free-ammonia/nh3.html

A nice simplified graph (at 25C only) is shown at:

http://compost.css.cornell.edu/odors/ammonia.html

And the old warhorse, but still valid:

http://fins.actwin.com/aquatic-plants/month.9507/msg00139.html

HTH


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## dennis

I saw several of those charts when I was searching about this reciently. Honestly I don't think they have any merit in this situation because I don;t think the plant and algae care whether it is NH3+ or NH4+. Plants/algae can easily get the N from eithe rof those with out expending more energy than it is worth. That is why algae blooms canbe triggered by NH3/4. They have evolved to recognize situations of higer than normal levels in their environment and increase their growth rate accordingly.

I think, and this is just speculation, but looking at the chemical formula for the chemicals Salt posted as being in Seachem stuff, they are not NH3/NH4 but rather 2 NH2 molecules bound to C and or O molecules. I have reached the limit of my chemisrty here again but possibly those would be more stable. The algae might not be able to strip down those molecules to get at the individual elements while the higher plants should be able to break down the bonds pretty easily. Same as Excel works as a carbon source. The algae have no real use for the chemicels in Excel but the plants can easily break it down to get at the carbon.

Course, as usual, ther I go hypothesizing without any proof....


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## RTR

The post I did on the NH3/NH4+ equilibrium was basically to refute Raul-7's report on the Seachem tech support contention that below neutral is ammonium ion and above neutral is the dissolved gas - which is such a terrible misunderstanding and distortion of the equilibrium that it is pathetic. I would hope that the folks here are aware of the massive difference between such distorted statements and reality. If not. they can review the non-commercial sites ref'd and see for themselves.


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## Raul-7

They're at an equilibrium at a pH of 9; but NH3 begins to rise after a pH of ~7.5 and NH4 begins to decline at the same ~pH. At a pH of lower than 7.5; most of the ammonia is NH4 (NH3 + H+ --> NH4). But then again, there is still a lethal amount of NH3 at a pH of 6.5. I'm assuming NH3 won't be lethal at a pH of 6 and lower if the temperatrue stays at a constant 77F?


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## BryceM

Can I just throw my two bits in about the chemistry of this? Nitrogen gas dissolved in a liquid does nothing - it is completely inert. Ammonia (NH3) is toxic to fish, much more than a related compound, ammonium (NH4+). If you add any ammonia to water, a portion of it will turn into ammonium by reacting with water molecules.

NH3 + H2O <---> NH4+ + OH-

This reaction can go either forward or backward. In a basic solution (such as pH 8, there is already plenty of OH- around so the equation tends to go to the left (more ammonia). In an acidic solution (such as pH 6, there is very little OH- around, favoring the reaction going to the right (most ammonia converts to NH4+). The reaction is also dependent on temperature, but not as much.

To be toxic to fish, you need a certain concentration of ammonia in water. One of the above links gives some good ballpark concentrations. You can get ammonia toxicity even at a pH of 5 if you add enough (very rare, but could be done with enough windex, for example). For comparison, a very small amount of added ammonia would produce the same toxic concentration at a higher pH.

BTW, none of this has anything to do with potassium bicarbonate, which is the title of this thread.

Plants love NH4+, using it as their preferred source of nitrogen when it's available. As soon as molecules of NH4+ are removed by the plants, the above equation shifts a bit (to the right), and more NH3 is converted to NH4+. In a sense, it 'looks' like the plants can use either NH3 or NH4+ since they both exist in equilibrium in any solution.

Plants are also perfectly capable of using NO3- as a nitrogen source and it's much better tolerated by the fish (as we all know from the nitrogen cycle in non-planted aquariums.) Per some research done by Tom Barr, it seems that NH4+ has a detrimental effect when it comes to algae (exactly why has not been explained to me). In a healthy planted tank, the ammonia made by the fish should disappear quite quickly into the plants. Measurable concentrations of ammonia should be zero. Reasonable additions of NO3- don't seem to cause the same algae blooms, but still make Nitrogen available to the higher plants.

One of the readily available commercial fertilizers is ammonium nitrate (NH4NO3). Lots of nitrogen to go around..... It should be easy enough to find if someone wants to experiment with it. For that matter, pure ammonia isn't that hard to find either. Personally, I'll stick with my KNO3.


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## perpacity

Food grade Potassium Bicarbonate can be found relatively cheaply here: http://www.thegrape.net/browse.cfm/4,10297.htm


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## Salt

Cool! Thanks for the link! 

I think it sometimes goes by the name "Salt of Tartar." I have been using it ever since January with no problems.


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## kekon

I use NH4NO3. I works quite well but i think i have to increase the daily dose. I add 0.2 ppm and 0.68 ppm NO3 daily from NH4NO3. The NO3:NH4 ratio is 3.4.
There aren't any algae issues. The whole story about NH4 causing algae is an exagerration. Some folks add 1 ppm NH4 daily without any problems with algae. My NO3 reading is still close to zero so that's why i'm thinking of increasing the daily dose of NH4NO3. However it is not a good thing to dose only NH4 as it's consumed by plants in a matter of a few hours so slower growing plants may not "notice" NH4 as a source of N and they will be N starved. One needs to dose NO3 together with NO3.
A commercial N fertilizer "Eudrakon" by German company "Drak" is a composition of KNO3, urea and NH4NO3.

*As regards to K2CO3 - don't use it !* It's a strong base (pH in water solution is about 12) and it has very negative effect on plants ! I used it for a week or so and it caused severe stunting ! Many people confuse K2CO3 with KHCO3. KHCO3 is very best source of K and it is used in ADA Brighty K - not K2CO3 as some people said ! The reason why K2CO3 cause stunting is not well known. I read that it is cinnected with "K2" ions vs "K" ions but i dont't think it matters because we add K from K2SO4 without problems with so called "K2" ions.


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## Salt

I had posted and guessed it might have something to do with K2 vs K, but that was a *wild* guess.


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## kekon

Many people are obssesed by the fact that NH4 causes algae but i think they've never checked it. I added NH4 into my tank and never had any algae bloom. To induce algae bloom by adding NH4 we must add a lot of it - at least 1 ppm daily or more. A person i know added even 2 ppm without any algae issues. The reason that some kinds of algae may grow when only NH4 is used as a nitrogen source is that NO3 drops to zero; when this happens GSA algae appear. This also happens when only NO3 is used. I always have GSA when NO3 is close to zero - no matter if i add NO3, NH4 or urea into the tank. I suppose that green water appers only when very high amounts of NH4 or urea are in the water column.


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## Troy McClure

kekon said:


> *As regards to K2CO3 - don't use it !* It's a strong base (pH in water solution is about 12) and it has very negative effect on plants ! I used it for a week or so and it caused severe stunting ! Many people confuse K2CO3 with KHCO3. KHCO3 is very best source of K and it is used in ADA Brighty K - not K2CO3 as some people said ! The reason why K2CO3 cause stunting is not well known. I read that it is cinnected with "K2" ions vs "K" ions but i dont't think it matters because we add K from K2SO4 without problems with so called "K2" ions.


It's been a loooong time since I've had to deal with real chemistry, but this got me thinking....keep in mind I really have no idea what I'm talking about! 

With regards to KHCO3 (potassium BIcarbonate) versus K2SO4 - you have a potentially more bio-available potassium form and a change in alkalinity versus a potentially less bio-available for of potassium and no affect on alkalinity? Is that correct? Does Brighty-K have any affect on alkalinity, or is that effect negligable when using KHCO3? Would the stunting difference between K2CO3 and K2SO4 have to do with how the carbonates and sulfates are broken down? What kind of K:CO3 ratios are we talking about with KHCO3? I found this decade-old post by Paul Sears -



> "at KH 4, the concentration of HCO3- is 1.42 mM (millimolar),
> and if it all comes from KHCO3 [starting at kH of zero], the concentration of K would be the
> same (before the plants started consuming it). This means you would
> have about 56 ppm of potassium in the water."


I understand K2SO4 is the generally accept source of potassium. I'm just curious as to what the best source of K is and what other effects that chemical has on water chemistry. K2SO4 adds sulfur to the water but we dont' really care about that, so I'm wondering -if- KHCO3 is the "best" source of potassium, maybe the carbonate it adds is something we can overlook in an attempt to give our plants better potassium and therefore better nutrient assimilation, less stunting, etc.


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## kekon

Frankly, i'm not a chemist so i'm not any good at it... Anyway, now i use KHCO3 and it turns out it doesn't raise KH so much as it seems. I added 12 ppm K throughout a week from KHCO3 and it should have raised KH of 1.7 but it raised 0.5 only. Maybe because plants are uptaking the K and some of HCO3 ions together. As far as i know some plants are able to use CO2 from HCO3.


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## Revan

Hi Kekon, you have probably made a mistake in the calculations: 

KHCO3 --> K+ + HCO3-

1°dKH = 21.76mg/l HCO3-

12mg/l K+ --> 30.769mg/l KHCO3 --> 18.76mg/l HCO3- --> 0.86°dKH

Best Regards


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## kekon

Yes, you're right. I confused KHCO3 with CaCO3 when calculating KH. Thanks for correction.
This is good thing to know, though  It means KHCO3 doesn't raise KH so much.


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## Revan

Salt said:


> K = 39.0983 moles
> H = 1.00794 moles
> CO3 = 60.0089 moles
> 
> KHCO3 = 100.11514 moles
> 
> 1 / (60.0089 / 100.11514) = 1.668338 mg to raise CO3 1 ppm in 1 liter
> 17.853037 mg to raise CO3 10.70109 ppm (1 dKH) in 1 liter (note this is nearly equal to calcium carbonte)
> 67.581101 mg to raise CO3 10.70109 ppm (1 dKH) in 1 gallon
> 
> Potassium - 1 ppm in 1 liter:
> 
> 1 / (39.0983 / 100.11514) = 2.560601 mg to raise K 1 ppm in 1 liter
> 1.668338 mg / 2.560601 mg = 0.651542 ppm K increase for every 1 ppm of carbonate increase
> 
> Example - Raise RO/DI water 5 dKH with Potassium Bicarbonate:
> 
> 5 dKH = 34.8610479039 ppm Potassium
> 
> Not looking bad at all.


Hi Salt,

for calculate alkalinity you have to consider "equivalents" not "moles":
http://en.wikipedia.org/wiki/Equivalent_(chemistry)
http://en.wikipedia.org/wiki/Alkalinity

Read for example this article:
http://fins.actwin.com/aquatic-plants/month.9801/msg00174.html

1°dKH = 21.76mg/l HCO3-
1°dKH = 10.71mg/l CO3--

because

mw = molecular weight

mw CO3-- = 60.008
mw HCO3- = 61.015

mM = millimolar = mmol/l = millimole/l
meq = milliequivalent

21.76mg/l HCO3- = 21.76/61.015 = 0.357mM = 0.357meq/l
10.71mg/l CO3-- = 10.71/60.008 = 0.178mM = 0.178*2 = 0.357meq/l

to convert mM in meq/l you have to multiply by the ion's charge.

So 1°dKH = 21.76mg/l HCO3- = 35.69mg/l KHCO3

Best Regards


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## Salt

1 degree if alkalinity is equal to 17.84799 ppm of CaCO3. CaCO3 is 60% CO3, so there is 10.701084 ppm CO3 in 1 dKH.

The atomic weight and percentage of carbonate in KHCO3 is nearly the same as CaCO3, so the measurements would be the same.

I'm not a chemist, but I have always understood the calculation method I use to be correct.


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## Revan

Hi Salt, this is the full calculations:
http://www.webalice.it/ccappelletti78/GH_KH.xls

I'm not a chemist so I can't explain more precisely but consider that alkalinity is something related with the capacity to combine with H+ ion so CO3-- can be combined with 2 H+ ion; HCO3- with only one H+ ion (it's why I consider "equivalents" and not "moles")

In the article that I linked in my last post it is explained in a different way..... but with the same resoult.
http://fins.actwin.com/aquatic-plants/month.9801/msg00174.html

You can find another good article about alkalinity here:
http://www.advancedaquarist.com/issues/feb2002/chemistry.htm

I'm sorry for my bad English

Best Regards


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## Newt

Good thread worth ressurrecting for a read.


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## AaronT

Newt said:


> Good thread worth ressurrecting for a read.


Too funny. I was just reading this to try to find how much KHCO3 to add to raise my KH using reconstituted RO.


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## Newt

That is quite the coincidense.
I was reading it as I heard Potassium Bi-carbonate was good to dose for anubias fungus. Apparently, the fungus doesn't "like it".

What I'd like to know is where have all those (and other) old members gone?


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## AaronT

In case anyone is still wondering about using potassium bicarbonate to raise KH I came across the answer. 

67.7 grams of KHCO3 in 500 ml of distilled water

1 ml / gallon = 1 dKH
1 ml / gallon = 14 ppm K (potassium)


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## Zapins

Old thread but I'd like to start using potassium bicarb.

Does this stuff look like the right stuff to use?

http://www.ebay.com/itm/Potassium-B...Equipment_Lab_Supplies_ET&hash=item3cccb9d35c

I see it says "Potassium hydrogen carbonate Formula: KHCO3" and that it is 99.5% pure which is more than you can say for the other stuff for sale on ebay...

But bicarb is a different formula no? Is this the right stuff?


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## JeffyFunk

Zapins said:


> I see it says "Potassium hydrogen carbonate Formula: KHCO3" and that it is 99.5% pure which is more than you can say for the other stuff for sale on ebay...
> 
> But bicarb is a different formula no? Is this the right stuff?


Carbonate is the CO3-- anion; Bicarbonate is the HCO3- anion.

I've bought KHCO3 from the local wine making shop - it's used to neutralize some of the acidity. I can't say i really noticed any difference between using KHCO3 vs K2SO4 as an extra K source... but i also admit that i wasn't really looking carefully so it's possible i missed some positive or negative changes in my plants.

Also, supposedly ADA Brighty K is K2CO3. I can't remember who tried that but the carbonate anion is very basic and they had an adverse plant reaction. For that reason alone, i'd stick with KHCO3 since it's less basic.


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## Zapins

OK thanks, so the stuff in the link is the right stuff.


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## Yo-han

That is the one I use as ADA brighty K knockoff. K2CO3 is quite basic indeed so I'm not sure how useable it is in an aquarium.


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## AaronT

Yeah, that's the right stuff Zapins, but you can find it cheaper than that. I got mine here. 
http://www.carolina.com/specialty-c...=&sCat=&ssCat=&question=potassium+bicarbonate

Reagent grade is pretty pure and shipping was $8 on two bottles of it.


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## John Talbert

With potassium bicarbonate raising pH a bit, doesn't that allow for more CO2 injection? And since CO2 <> H2CO3 <> HCO3 <> CO3: adding bicarbonate (HCO3) should push out more CO3 or available carbon as a result, yes?

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## Diana K

The idea is right, but with so many other things going on in the tank I am not sure if you would see it. 
If you tried to add both CO2 (pressurized) and H2CO3 then it sure looks like the end result would be a shift toward more CO3. I am sure that would happen in a test tube.


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## gjmelb

First of all, I apologize for reviving an old post. It was very interesting and informative reading but also overwhelming at the same time. 

Now to make my life easy and simplify things, I have improvised a bit. I use a jewellery scale for weighing chemicals which gives me readings in grams upto 2 decimal places. For water parameters I use Api drop tests which use the units of ppm for the colour chart and dKh for alkalinity. So from the above equations I've concluded to;

Use 0.026g/l of KHCO3 to raise K by 10ppm and Kh by 1.4dKh.

For those using gallons just multiple by 3.78 ie 0.098g/gl (grams/gallon).

I hope I've calculated correctly and it would help other newbies like me... cheers!


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## JuliaAdkins

Some misconceptions here start with although fish waste includes ammonia and nitrites, these are toxins for fish and other critters. Ammonium nitrate is not a good thing to add to a tank. I would totally stay away from any ammonia or ammonium anything. 
Barrs GH Booster contains magnesium sulfate (1 part), calcium sulfate (3 parts) and potassium sulfate (3 parts) by weight. It is an excellent water conditioner. If there are difficulties with solubility you can add a very small amount (1 tsp to 500 ml water) of cider vinegar to increase solubility. 
Greg Watson is no longer in the fertilizer business and has not been for 9 years. Greg is still an excellent resource for dosing information.


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## Yo-han

Not totally true. Plants prefer ammonia over nitrate, but it is toxic for your fauna when too much is present. I do use it in my fertilizer and animals are all fine. It all depends on pH, temperature and concentration. I wouldn't recommend it for beginners though unless you now exactly what you're doing.


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