I would appreciate some advice determining what size/brand sand filter I should buy. I need to buy replacement filters soon which I estimate will be $350-400 for my system, so this would be a good time to make the change. i would like to switch to sand to lower my maintenance time. I really dislike cleaning the filters - takes forever to get them clean, and my unit was installed too close to the house so I always get bloody knuckles from the stucco, when taking off the clamp assembly. My pool is 18k gallons, and I run it 8 hours most of the year (swim season with solar heat is 8-9 months where I live). So at 37.5 gpm divided by 15 gpm sq. ft, I would need 2.5 sq. ft. - do I rounded to 3? As for brands, I have no clue or preference. My current stuff is all Hayward. I don't want to ask my original pool installers - found out well after the fact that they sold me a filter system twice as big as I needed. My pool store is fine for chemicals and repairs, but dummy me way overpaid for a replacement cell for my SWG. I could have saved $200 on Amazon and $75 install. Didn't realize that the thing just plugs in! Any assistance or advice appreciated.