Hi all,
The problem has a lot to do with the pH scale, which is a ratio. Because it is a ratio it doesn't tell us anything useful about amounts.
At pH7 we have equal amounts of acids (H+ ion donors) and bases (H+ ion acceptors) in solution, but we don't know what that amount is, it could be 1:1, 100:100 or 100,000:100,000, pH doesn't change, as long as acids and bases are in balance.
If you keep fish from salt rich, buffered alkaline water (Lake Tanganyika etc) small changes in pH reflect large changes in water chemistry. If we start with very hard carbonate buffered we have a huge surplus of bases and we need to add an equally huge amount of H+ ions to reduce the pH. If we keep fish in very soft water any small change in water chemistry, in the amount of acids or bases, has a large effect on the acid:base ratio, and changes the pH. The pH can't be stable.
In this scenario I've added a very small amount of very weak acid (like H2CO3) to be in our heavily buffered water neutral water. We now have a ratio of 100,001:100,000 (H+ donor:H+ acceptor) and no change in pH, in our lightly buffered water we have a ratio of 101:100, and very little (if any) change in pH, but in our very soft water we now have 2:1 acid:base and our pH "crashes".
Does this pH crash kill your fish? No it doesn't. How do we know? because it is what CO2 users do every day when they turn the CO2 on. When they turn the CO2 off, CO2 levels equilibrate with atmospheric levels, and pH returns, just as rapidly, to its initial value.
cheers Darrel
I'd have to agree with Clive, it is an article that contains a lot of "facts" some true, some not, but all of them irrelevant, or only tangentially relevant, to the issue.The article provides comprehensive coverage of the three most popular obsessive parameters, pH, KH and GH. Unfortunately the information provided is completely irrelevant.
The problem has a lot to do with the pH scale, which is a ratio. Because it is a ratio it doesn't tell us anything useful about amounts.
At pH7 we have equal amounts of acids (H+ ion donors) and bases (H+ ion acceptors) in solution, but we don't know what that amount is, it could be 1:1, 100:100 or 100,000:100,000, pH doesn't change, as long as acids and bases are in balance.
If you keep fish from salt rich, buffered alkaline water (Lake Tanganyika etc) small changes in pH reflect large changes in water chemistry. If we start with very hard carbonate buffered we have a huge surplus of bases and we need to add an equally huge amount of H+ ions to reduce the pH. If we keep fish in very soft water any small change in water chemistry, in the amount of acids or bases, has a large effect on the acid:base ratio, and changes the pH. The pH can't be stable.
In this scenario I've added a very small amount of very weak acid (like H2CO3) to be in our heavily buffered water neutral water. We now have a ratio of 100,001:100,000 (H+ donor:H+ acceptor) and no change in pH, in our lightly buffered water we have a ratio of 101:100, and very little (if any) change in pH, but in our very soft water we now have 2:1 acid:base and our pH "crashes".
Does this pH crash kill your fish? No it doesn't. How do we know? because it is what CO2 users do every day when they turn the CO2 on. When they turn the CO2 off, CO2 levels equilibrate with atmospheric levels, and pH returns, just as rapidly, to its initial value.
cheers Darrel