# What do you use to raise KH, Sodium Bicarbonate(baking soda) or Potassium Bicarbonate



## hooha (Mar 14, 2004)

I use sodium bicarbonate because it's easily available.....whether or not the extra sodium leads to problems with plants, I haven't seen it myself.


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## Rex Grigg (Dec 10, 2002)

Excess potassium doesn't interfere with calcium or magnesium. Tom Barr shot that one down a while back.

And the sodium in sodium bicarbonate doesn't harm plants.

Also sulfates alone do not produce hydrogen sulfide gas.


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## Naja002 (Oct 12, 2005)

And you do not need to adjust/add Kh for RO water---just use 100% RO. :thumbsup:


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## Ryan Monroe LA (Nov 11, 2007)

*reply*

Rex, there are limits everything, and I can assure you it is a well known agricultural fact that, at least terrestrial soils, magnesium and calcium availability can be affected by potassium overfertilization. I have personally witnessed magnesium defficiency on some of my palm trees after fertilizing heavily with a high-potassium granular fertilizer.

The same goes for the use of sodium bicarbonate. Theoretically, there must be some KH level (I'm guessing 10-14 deg KH) where the sodium in the sodium bicarbonate would begin affecting the plants. But I believe you that at the most commonly used planted aquarium KH levels (3-8 deg KH), it is almost certainly not harmful. I'm probably going to start using a half/half mix of sodium bicarbonate and potassium bicarbonate to add KH.



Naja002 said:


> And you do not need to adjust/add Kh for RO water---just use 100% RO. :thumbsup:


Naja, I hope you are suggesting using pure RO water only to top off for evaporation? Do you understand how wildly the pH can swing in an aquarium with no buffering capacity (KH)? Even if you could somehow maintain a stable pH, I'm pretty sure most plants prefer to have at least a few degrees of KH!


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## Rex Grigg (Dec 10, 2002)

Terrestrial plants are different than aquatic plants. I suggest you not try and apply terrestrial traits to aquatic plants.

And note your own statement. 



> fertilizing heavily with a high-potassium granular fertilizer


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## Naja002 (Oct 12, 2005)

Ryan said:


> Naja, I hope you are suggesting using pure RO water only to top off for evaporation? Do you understand how wildly the pH can swing in an aquarium with no buffering capacity (KH)? Even if you could somehow maintain a stable pH, I'm pretty sure most plants prefer to have at least a few degrees of KH!


I am suggesting 100% RO. Top-off and otherwise. The pH swing and lack of stability is an old school myth. I used 100% RODI when I was running my unit, and I learned from others:

Low or no KH and low PH without a "crash"??

Low KH and pH crash 

pH = 5.5, what now? 

Excellent results......:thumbsup:


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## fishscale (May 29, 2007)

Man, you guys and your soft water. Wish I had soft water.


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## Ryan Monroe LA (Nov 11, 2007)

*well,*



Naja002;The pH swing and lack of stability is an old school myth. I used 100% RODI when I was running my unit said:


> Low or no KH and low PH without a "crash"??[/URL]
> 
> Low KH and pH crash
> 
> ...


The lesser pH stabilty associated with lower kH isn't a myth, it's a FACT of chemistry. Does that mean a hobbiest can't use low or no KH water and still be successful? Heck no. What it does say is that there is a lesser margin for error. In a tank with a high KH, you might be able to get away with a high fishload and no water changes for years, but in a tank with low KH, you might only be able to get away with such neglect for a few months. Now if you are a good aquarist, you'll probably never need to worry about such things.


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## Naja002 (Oct 12, 2005)

Ryan said:


> Now if you are a good aquarist, you'll probably never need to worry about such things.



Well, let us know when you reach that point......:thumbsup:


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