We are very new to the pool world. We bought a house with a in ground 1985 pool and until this week the old cartrige filter worked fine. The o-ring just died and we decided to go with a sand filter. I noticed that some people suggust putting in a bigger filter then is called for. Can anyone suggust a brand and size for our 8000 gal pool? The pool is 12 by 24 (300SF) and is five feet on the deep end and 3 feet on the other end. Thanks in advance.