I have a very old Baker Hydro RV-24 sand filter that was originally designed for an above ground pool from what I have been told, but it has worked pretty well for us since we bought the house. It's been about 25 years now and it needs to be replaced and I'm not sure if a sand filter or cartridge filter would be the way to go for a replacement. It's a 16 x 32 in ground liner with about 26,000 gallon capacity. Any recommendations?