Hmm see now in my breeding tanks I'll do once a day changes of 20% with cooler water it's always been a habit of mine. In the rest of my tanks that aren't housing fry or young ones, I do a water change every other day of about 40-50% I don't ever put primer or any of that in just because I simply live on a well system, my ph is at 6.5 and every fish I've ever kept has thrived in it.