Large water changes input

[waynemah]

Originally Posted by Aquattro

Not sure what the concern is on water changes. Where does this common 20% come from? Not sure how too much clean water is going to hurt your fish, given that the important parameters match.

I threw 20% out there because It's what I've had experience with. Personally if it came down to it and fish were dying, I'd do as large of a water change as fast as possible. But I don't want to be responsible for crashing someones tank with inexperienced recommendations.