Above Ground Pools
Above ground pools need the same water chemistry as in-ground pools, but they have their own quirks. Smaller volume means chemistry changes faster. Lighter construction means you need to be more careful with equipment. Here is everything you need to know.
The chemistry rules for an above ground pool are identical to an in-ground pool. You need the same free chlorine range (2-4 ppm), the same pH range (7.2-7.6), the same alkalinity range (80-120 ppm). The difference is that in a smaller body of water, everything changes faster.
A 5,000-gallon above ground pool will heat up faster in the sun (algae loves warm water), lose chlorine faster, and react more dramatically to chemical additions than a 20,000-gallon in-ground pool. This means you need to test more often and add chemicals in smaller doses.
| Pool Size | Approximate Volume |
|---|---|
| 12' round x 48" | 3,400 gallons |
| 15' round x 48" | 5,300 gallons |
| 18' round x 52" | 8,600 gallons |
| 24' round x 52" | 15,200 gallons |
| 12' x 24' oval x 52" | 8,600 gallons |
Volumes are approximate. Knowing your pool's volume is essential for correct chemical dosing.
Most above ground pools come with small cartridge filter pumps. These are adequate for basic filtration, but they need more attention than the larger sand or DE filters found on in-ground pools.
Run the pump at least 8 hours a day. The entire volume of the pool should turn over at least once per day. For a 5,000-gallon pool with a 1,000 GPH pump, that is about 5 hours. But algae grows when water is stagnant, so longer is better.
Clean or replace cartridge filters regularly. A clogged cartridge filter restricts flow dramatically. Rinse it weekly with a garden hose. Replace it every 2-4 weeks during heavy use, or when it will not come clean anymore. They are inexpensive and worth replacing often.
Small pools in direct sun lose chlorine fast. If you are using trichlor tablets in a floater, they may not dissolve fast enough to keep up. Consider switching to liquid chlorine added every 2-3 days, or increase your tablet dosage. Always maintain CYA at 30-50 ppm to protect chlorine from UV.
Groundwater pressure under the pool can push the liner up. This happens after heavy rain. The fix is to keep the pool water level higher than the surrounding groundwater. In extreme cases, you may need to drain and reset the liner.
Small volume means less buffering capacity. Add chemicals in small doses, wait at least 30 minutes with the pump running, then retest before adding more. It is easy to overshoot in a small pool.
Above ground pools have less circulation near the walls and floor. Brush the walls once a week. A manual vacuum or inexpensive robot cleaner helps keep the floor clean. Good circulation prevents most algae problems.
If you live in a climate where it freezes, you need to winterize your above ground pool. Balance the water chemistry, shock the pool, add winterizing chemicals (algaecide and scale prevention), lower the water level below the skimmer return, disconnect and drain the pump and filter, and install a winter cover.
Do not drain an above ground pool completely for winter. The water weight helps support the walls and keeps the liner in place. A completely empty pool can collapse from wind or snow load.
Pool Clarity works with any pool size. Enter your volume, log your test results, and get exact chemical dosing for your pool. Free to use.