Ok, so we're setting up our pool, 15'x4' round metal frame intex. Last year even using this method was a pain once the water got warm (we live in the south) so was going to get a swg. I calculated my pool at 5600 gallons. So I'm looking at the intex swg and they come in 7000 or 15000. I have a big sand filter so will 7000 be plenty or is there some hidden advantage to going with the bigger one even though I don't need it? Just want to double check since its intex (all I see in swg) and they're known for claiming a cartridge filter can work on a 15' pool but really it's way too weak (why we switched to sand)