Making a long-lasting sand filter for your above-ground pool is a simple task that requires only a few materials. It can supplement or replace the cartridge filter you are currently using, and it needs cleaning, on average, only once a year. Follow the steps below and try out this solution to a clean pool.
Step 1 - Obtain the Materials for Your Filter
Purchase a 10-gallon, tall, rectangular, clear plastic storage container with a tight-fitting lid. Scooping up any old sand for your filter won't work, so head to any pool supply store to buy filter sand specifically; it has specially shaped small grains that trap pool debris effectively.
You can recycle old nylon stockings for this project as well, but use a high denier (woven thread count) type so they will filter the water thoroughly. Super-sheer nylons will not stand up to the abrasion of the sand grains or the water pressure through the pool pump.
Step 2 - Assemble the Sand Filter
Using a drill, punch two round holes in the container, one in the middle of the lid and the second on one of the narrow container ends, half an inch above the bottom. Make the holes the same diameter as your pool pump filter tubing. Then, run a length of tubing from the top of the pool down to the sand filter container.
Put your sand filter close to the cartridge filter and pump for convenience. Insert a second tube into the bottom of the sand filter container that will take filtered water back to the pool pump. Seal both of the openings around the tubes with 100 percent silicone caulking to ensure it is waterproof. Place a section of one leg of the nylon stockings over the opening of the bottom tube, fasten it firmly with black waterproof plumbing tape, and caulk it with the silicone sealant to hold it firmly.
Step 3 - Add the Sand to the Filter
Remove the filter lid and pour the 10-pound bags of pool sand into the container. Spread it out so it is level and fills up to 3/4 of the container's depth. When the water enters it should spread out evenly across the top of the sand filter medium. Place the lid snugly on the container once it is full, and tie down the lid with strap clamps so you can release the lid again when the sand needs cleaning. When the sand darkens to a greenish-black color, it must be cleaned.
Step 4 - Turn on the Pool Pump and Test Your Filter
If your filter is leaking at either its entry or exit port, repair it with more caulking or make and attach a new tube. Check your sand filter's operation weekly. As a result of adding the sand filter, your cartridge filter should require cleaning far less often. If your sand filter is doing the job by itself, you can remove the cartridge filter from the system altogether.