We bought a sand filter for our 18' Intex pool and it has done wonders for our pool water. We have 80ppm iron in our water, when we filled our pool it was so brown that you couldn't see 6 inches down. We let our sand filter do it's job with a little help from us with brushing the floor and sides of the pool to keep the iron floating in the water....48 hours later we have a clear pool. We went with a 3/4 HP Sand Filter System made by G.A.M.E. It was $300 but it was the best money we've spent Good luck!