How to raise ph?

[AmyKieran]

I am trying to raise the ph of my Malawi tank with little success. I have used about 4kg of limestone rock in the tank as well as about 200g of crushed coral in the filter and the ph is still at 7. I have ordered another 1kg of crushed coral for my filter. Do you think this will be enough to raise it? I have read using ph up will raise it then the crushed coral will keep it there, any other suggestions other than that method?

 

[itiwhetu]

I have always used limestone chip for the base of my African Cichlid tanks and have never had a problem with pH.

 

[AmyKieran]

I have always used limestone chip for the base of my African Cichlid tanks and have never had a problem with pH.

Yeah I’ve also read using a different substrate but I really like the substrate I have in there so I ideally didn’t want to change

 

[GaryE]

As always, what happens depends on your starting water. You must do water changes, so if you have super mineral free tap, you dilute your progress as you go.

I'm a softwater fishkeeper who had hardwater when he kept Malawis, so I never dealt with this. But I know you can buy rift lake salts - mixes that are added every water change.

 

[Uberhoust]

Limestone varies a lot, much of it is graded with magnesium carbonate, dolomite, the dolomite version is no where as soluble in water as pure calcium carbonate, and hence cannot buffer the water as well. Additionally the size of the limestone pieces affects the exposed surface area and its ability to raise the pH. The crushed coral should have an influence but that will depend on the flow through your filter and the size of the tank. It has been a while since I have raised Mbunas, but when I was I had about 50-75 pounds of limestone in a 70 gallon tank and gravel that was approximately 20% crushed shell. I did not use any additional pH adjustors but my input water was also slightly on the alkaline size i.e. 7.2 to 7.5.

 

[Byron]

You don't mention GH and KH, and these are part of the equation as others mention. What are the numbers for the tap water on its own, the GH, KH and pH?

And, do not resort to chemicals like pH up, these do cause issues for fish and they generally fail because again it is the chemistry of GH/KH/pH that is the crux. [Mineral salts and natural hard minerals are not the same as the chemicals, just to be clear].

 

[itiwhetu]

The fine limestone chip we have in New Zealand worked for me, and I using rainwater as my starting point. I raised Electric yellows in it.

 

[itiwhetu]

By the time you try to figure out all the things above you will end up doing nothing. I have a simple fix, that has always worked for me.
What I want to know is what do you do with all the numbers on a piece of paper how do they help you with a solution
If the numbers are so and so you do this, if they are so and so you do that, I have never seen a chart that shows how knowing the KH GH helps with these exercises.

 

[StevenF]

I am trying to raise the ph of my Malawi tank with little success. I have used about 4kg of limestone rock in the tank as well as about 200g of crushed coral in the filter and the ph is still at 7. I have ordered another 1kg of crushed coral for my filter.

Limestone varies a lot, much of it is graded with magnesium carbonate, dolomite, the dolomite version is no where as soluble in water as pure calcium carbonate, and hence cannot buffer the water as well.

Pure calcium carbonate and magnesium carbonate ONLY dissolve in acidic conditions PH less than 7. If the acidity is from excess sulfates or chlorides the carbonate will convert to PH nuetral calcium / magnesium sulfate or chlorides. If the acidity is from CO2 calcium carbonate converts to calcium bicarbonate. If the PH is above 7n the calcium bicarbonate slowly converts back to calcium carbonate. So with just limestone or coral You PH is going to stay at 7. Calcium and magnesium carbonate by themselves will not push the PH up to 8. However other minerals in water can change the carbonate PH. For example sea water with all the salt in it has a PH of 8 instead of 7 of fresh water.

 

[itiwhetu]

Pure calcium carbonate and magnesium carbonate ONLY dissolve in acidic conditions PH less than 7. If the acidity is from excess sulfates or chlorides the carbonate will convert to PH nuetral calcium / magnesium sulfate or chlorides. If the acidity is from CO2 calcium carbonate converts to calcium bicarbonate. If the PH is above 7n the calcium bicarbonate slowly converts back to calcium carbonate. So with just limestone or coral You PH is going to stay at 7. Calcium and magnesium carbonate by themselves will not push the PH up to 8. However other minerals in water can change the carbonate PH. For example sea water with all the salt in it has a PH of 8 instead of 7 of fresh water.

That is useful information, how do you raise the pH?