Of all the components to an above-ground pool's mechanics, the one that anyone can build is a filter. Anyone with basic plumbing skills and access to pool sand can accomplish this in a matter of hours. A pool's sand filter works by trapping contaminants and particles between the grains of sand as the water enters the filter, then preventing their release into the swimming pool. As more particles get trapped in the filtering sand, the less space is available between the sand particles, and the sand filter traps even more unwanted debris.
How to Make Your Own Sand Filter: Prepping the Container
Place a plastic container next to the pool's pump. Make sure that it is in a convenient location for both filling it and eventually cleaning it when necessary. Put it out of the way of passers-by who may accidentally knock it over.
Drill holes in the container for both the incoming and outgoing water. One hole should be drilled in the center of the lid and the other about half an inch up from the bottom of the container.
Preparing the Hoses
Attach mesh or nylon to the ends of the incoming and outgoing water supply hoses. Make a tight seal with the plumber's tape or stainless steel clamps to hold the mesh to the hoses.
Insert the outgoing water supply line hose into the bottom hole of the container. Apply silicone or other waterproof caulk to the space between the container and the hose to create a seal.
Choosing the Right Sand
Fill the container three-fourths of the way with the pool sand. Note that attempting to use sand that is too coarse or too fine will impede the effectiveness of the filter. Use only pool sand available at a pool supply store.
Place the lid atop the container and insert the supply line into the top. Use the silicone or waterproof caulk again to create a watertight seal.
Testing and Maintaining Your Sand Filter
Test your pool's filter. Turn on the pump to see if there are any leaks in your sand filter. Use caulk as necessary to repair it. Be sure to give the caulk time to dry before testing its effectiveness.
Check the sand in your filter regularly. Change it when the color appears green or black. This is a great sign that the filter is working, but fresh sand will improve the efficacy of the filter.