You dump and refill daily? I'd go thru a LOT of water doing that. Mine are on rock, but they can dig around the pool into the dirt and turn the clean water dk brown within two hours. When mine is stinky enough I smell it before I get there is when I drain and refill. It's a pond not a pool. Big difference. It sure is a hoot to sit and watch them in the fresh water, isn't it? Winter is going to be interesting.