I scoop out about 1/4 of the water & replace it with clean water most days. I also have a circulating pump that I have set up as a little waterfall, as well as a submersible filter, I take both of them out & clean them every week or two and about every 4 to 6 months move my FBT's into a smaller aquarium and I take everything out and thoroughly clean it. It has been working OK, my frogs are very active and seem happy to me.