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How to Build a Pool Filter for Small Pools

How to Build a Pool Filter for Small Pools. Warmer weather brings the lure of using the pool. Not everyone's yard can accommodate an Olympic-sized swimming pool, but above-ground pools provide a refreshing break and family gathering place. To filter the pool water and keep it clean for family and friends, here's how to build a pool filter for a small pool.

Purchase a 100-gallon stock tank for your small pool. Rubbermaid makes a variety of these and you can find them in home improvement stores or stores that cater to farming needs.

Remove the drain plug in the bottom of the stock tank and cut a hole for a 4-inch closet flange and for the mounting holes. The closet flange looks like a larger version of a shower drain. Apply silicone to the stock tank before attaching the closet flange to create a seal.

Build a stand for the pool filter so that the stock tank is above the level of the pool. Leave a hole in the stand for the PVC pipe on the bottom of the pond filter.

Cement PVC pipe to the flange for the water to run from the pool filter back into the pool. Put a short length under the pool filter and use an angle joint and another length of PVC to run the water back into the pool. The lengths of the PVC will vary depending on the stand you construct.

Put a fine mesh screen over the hole in the bottom of the stock tank and put the tank on the stand.

Fill the pond filter with fine sand to act as a filtration material. Leave about a 6-inch space from the top.

Pump water into the top of the pond filter. The force of gravity will pull water through the sand and return it to your small pool.


Adjust the water flow of the pump so that water flows out the bottom and does not come over the top of the pond filter. This will vary according to the type of water pump you have. These directions assume you have a small pool 12 feet wide by 4 feet deep. If your pool is larger, you will need to buy a larger stock tank, such as a 150-gallon one. If the 150 gallon pool filter does not work efficiently because of pool size, you will need to link another 150-gallon stock tank to the first or build a second platform on another side of the pool.


Don't try square tubs, old water heater tanks or 55-gallon drums. Stock tanks are built to last.

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