I have used them many times but the last batch was defective. It turned out that my tap water, which has a constant pH of 7.0-7.2, was below 6.0. It's easy to think the tank has a pH error when it doesn't, and accidentally make the tank too alkaline, which can kill your fish. I am farming 1 wild extinct species of fish, Monterrey Pied, and I just can't let this happen.
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