# low gh but high kh



## JTT84 (Feb 9, 2013)

Hi,
The Ph of my tap water is 8.2, kh is 15 degrees and gh is around 7.. I understand that a low Gh can make the Ph unstable, how do I bring the gh up without changing the Ph and Kh since they are in the right range for African cichlids?


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## k7gixxerguy (Jan 12, 2012)

Its my understanding that low kh causes instability in ph. I don't think that I would worry about your water at all but you can add some epsom salt during water changes to raise the gh. Remember that the salt stays from the water thats evaporated to so only replace salt for the actual volume of water that you take out, not what it takes to fill the tank back up if you have heavy evaporation.


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## Yael (Nov 25, 2012)

Just to make the calculations easier on myself, I always fill up the tank to a specific mark with fresh water (only chlorine treatment, nothing else) to replace any evaporation before doing a water change. If you keep the tank topped up you don't have to 'think' as much and are less likely to run into trouble.

Also remember that additive like baking soda won't make your pH go higher and higher. It's a buffer with a specific range over which it buffers pH. It will never take your pH so high that it'll be bad for African cichlids.

Bicarbonate as a buffer solution. A buffer is a solution which resists changes of pH upon addition of exogenous (outside) acid or base into the solution. For example, pure water has no or very little buffering capacity. Even a very tiny amount acid or base will cause the pH to swing from very low (less than 2.0) to very high (more than 9.0), respectively. Bicarbonate has some buffering capacity though quite weak. It works the best at the pH range around 8.5. Adding more will not tend to make your pH go higher than 8.5

Epsom salts has very little effect on pH. If it does anything it'll be to buffer pH at a lower level than baking soda. It does have effects on plant growth if you have plants in your tank. It can act as a fertilizer but too much of it will tend to make plant leaves curl.


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## JTT84 (Feb 9, 2013)

Oh ok, thanks for the tips!.. I really didn't want to add anything extra if I didn't need to since the ph and kh are fine. The gh is not too low but still lower than kh which is why I was worried. I might add epson salt, do you know how much epson salt per gallon? I have a 60 gallon tank. Thanks again.


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## JTT84 (Feb 9, 2013)

Topping it off seems like a great idea, that way I know exactly how much water I will be taking out. I will be using an aqueon water changer that takes the water out and into the sink and from the faucet to the tank, so I will have to take the water out and measure it in the buckets first and see where the water level is when I do 25% so I will know ahead of time. Thanks!


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## k7gixxerguy (Jan 12, 2012)

I think most people start with around a tbsp per five gallons for Epsom salt


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## Yael (Nov 25, 2012)

GH is made up of both calcium and magnesium - epsom salts only provide the magnesium. I think I'd crush up some limestone as a source of slow release calcium and call it good.


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## JTT84 (Feb 9, 2013)

Great, Thanks guys!


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