# Proper KH levels to stabilize ph



## mechanic_joe (Dec 4, 2003)

Hey all, I was reading another thread and it reminded me of a question about KH that I wanted to ask here. By my understanding, KH (carbonate hardness) is the water's ability to stabilize PH, and it is composed of bicarbonate, and carbonate ions.

So my questions are these: How does KH naturally drop in a tank (besides water changes of course) I believe I read that nitrifying bacteria can use it as energy ?

Why is it better to use a ph stabilizer that doesn't contain phosphates ? My IFS sold me a stabilizer that uses carbonic acid monosodium salts.

Thanks in advance

Joe.


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## mechanic_joe (Dec 4, 2003)

oh, and what is a good KH level to keep a piranha tank at, seeing as their water conditions lean towards being soft. 20 - 50mg/L ?

thanks


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## mechanic_joe (Dec 4, 2003)

Come on... I know I'm not the only one who doens't have any KH in the tap water, there must be other members that play with this reading ?


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## DonH (Jan 25, 2003)

In a river system, you don't have to worry about a pH crash but in a closed system like an aquarium, the process of nitrification and the resulting nitrates will drop the pH with time. Buffers in the water will nuetralize the acids but if the carbonates are not replenished (through water changes or addition of buffers), a pH crash will occur. A good range for KH is around 80-120 ppm. Any lower and you will have fluctuating pH.

The reason why phosphate buffers are not desireable is due to the fact that phosphates, with the presence of nitrates, will encourage an algae bloom.


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## mechanic_joe (Dec 4, 2003)

Thanks Don, I've found since I started setting my KH my ph has been very constant. Great info as always









Joe


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## sccavee (Feb 11, 2003)

DonH said:


> In a river system, you don't have to worry about a pH crash but in a closed system like an aquarium, the process of nitrification and the resulting nitrates will drop the pH with time. Buffers in the water will nuetralize the acids but if the carbonates are not replenished (through water changes or addition of buffers), a pH crash will occur. A good range for KH is around 80-120 ppm. Any lower and you will have fluctuating pH.
> 
> The reason why phosphate buffers are not desireable is due to the fact that phosphates, with the presence of nitrates, will encourage an algae bloom.


 So if nitrates are high, your PH can fall?


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## mechanic_joe (Dec 4, 2003)

> So if nitrates are high, your PH can fall?


 Uhm... the way I think of it is, the decomposition of waste creates acid, which lowers the PH. I think its more the nitrification process more than the actual nitrates.


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## DonH (Jan 25, 2003)

sccavee said:


> So if nitrates are high, your PH can fall?


 YES


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## sccavee (Feb 11, 2003)

Well that explains why I have low KH in one tank and not the other. Always wondered about that.

Have a hell of a time lowering my nitrates in my 75.


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