personally as they are good muck producers, i would run pumice with a prefilter of filterwool
whatever you use will probably need regular cleaning or water changes in the pool
i use the TLC Freshwater S.A.T on their pool to help the bacteria in the filter out
is the pool concrete or another material?
Donnam runs grass carpet on the edge of her pool to avoid the turts scraping the bottom of their shells
i have pumice here if you want it