I am looking for a little advice on possibly getting a new filter for my 18x48 Ultra Frame Intex Pool which holds 6423 gallons of water. I am currently using the pump it came with which is a Krystal Clear Cartridge Filter Pump 1500gpm. I don't want to spend an arm and a leg but I was wondering if a sand filter is a better choice or stick with the cartridge filter. I want to be able to use a normal vacuum and hook it right up to the filter so it would have to be powerful enough for that. Last year I had issues with green and I'm thinking if my filter was better I wouldn't have that issue. Granted I did learn I wasn't running it long enough so that mistake was rectified. It's just about time to put it up so I'd like to get everything needed ASAP. Thank you!