I have a large water tank (pool) in my iggys cage that's about 3 foot wide (his cage is 8ft). I put a waterfall filter in the water because removing that much water every day isn't feasible, so basically it filters the water and keeps in clean. My problem is, his poop is so dense sometimes that it just lands at the bottom of the water and stays there and never gets filtered. Then the water needs to be removed and replaced. When that doesn't happen the filter does it's job and keeps the water clean. I was wondering if anyone knew of a way to prevent that so I wouldn't have to replace the water so often. Just a way to keep it from settling on the bottom because if you don't allow it to settle then the filter cleans it properly. I was thinking aquatic sand for turtles may help but I don't know enough about it. For all I know it could make it worse not better and it would make replacing the water, if it doesn't work, a more difficult task. Just wondering if anyone has any experience or suggestions. Any help would be appreciated.