I have 4 albino cories in my 20 gallon long tank. I know cories do best in sand, so I got some black aquarium sand from petco. When I put it in, it raised the ph to over 9 and I lost half my fish. The other cories are barely alive and hardly eat or move. I am going to move them into a 5 gallon tub while I fix the ph.
What substrate should I get for the cories? I really don't want to risk getting sand again because there's a good chance it will mess with the ph. Also, pool filter sand only comes in white which would blend in with my cories and I really don't want to spend another $40+ on petstore sand only to have it fail again. Would cories be okay in black gravel? I know it can be hard on their barbels, but if it was smooth and pretty small, do you think it would work?