ditto; never used chems ever in 10 years now. Everything natural in a balanced system. Lowering or raising the pH generally is more problematic than not. Fish can acclimate and once they do (slowly, if you're introducing and the differential can't be that great), keep it stable. pH crashes do a lot of harm. Using the clariier (I'm assuming a UV light, here) is a bandaid; learn how to curtail alage growth naturally and you'll not ever need such gear (or chems).