I just did a 20% water change. Used a water conditioner and a pH lowerer as my tap water runs pretty high. I've been doing this every third day when I vacuum and it's been OK. Except today after I did it the pleco and the danios became ultra hyperactive. The danios are swimming in a circular chain around the pleco's algae pellet (then fighting when one of them nips at it) and the pleco is frenetically cleaning the walls. The gouramis and the betta are still acting normal though. Any ideas?