i gues now i'm looking into separation tanks (which should maybe be another thread). in addition to the innefficiency during backwash question above, does anyone here have experience using one where you return the separated water to the pool? most manufacturers say that you can do this, but it seems to me, that unless the tank filters as well as a de filter, you'd get a buch of crud making it past the sep tank and back into the pool. does anyone have any experience with this?