I tried going 3 days on the bigger baby pool, but really it needed every other day. So I bought a smaller infant sized pool, and change it every 2 days. Day one I fill it half full,, morning of day 2 I top it off to full, that evening, I dump it and leave it empty until the next morning. Works well. I gave the big pool back to the dogs, they were so happy to have their pool back!