How many gallons is a 21 ft round pool?
About 10,408 gallons at 4 ft of water. Above-ground pools this size have 48 to 54 inch walls, which leaves around 4 ft of water.
| Water depth | Gallons | Liters |
|---|---|---|
| 3.5 ft | 9,107 | 34,469 |
| 4 ft | 10,408 | 39,393 |
| 4.5 ft | 11,709 | 44,317 |
Chemical doses for 10,408 gallons
| To do this | Use | Amount |
|---|---|---|
| Raise free chlorine 1 ppm | Liquid chlorine 12.5% | 11 fl oz |
| Shock from 1 to 16 ppm (CYA 40) | Liquid chlorine 12.5% | 1 gal 32 fl oz |
| Shock from 1 to 16 ppm (CYA 40) | Cal-hypo 65% | 2 lb |
| Salt from 0 to 3,200 ppm | Pool salt | 277 lb 9 oz |
| Raise alkalinity 10 ppm | Baking soda | 1 lb 7 oz |
These are starting doses. Add, circulate for an hour, retest. For your own readings use the chlorine, shock, salt, pH and alkalinity calculators.
Full dose tables for the nearest round number: shock for a 10,000 gallon pool, chlorine for a 10,000 gallon pool, salt for a 10,000 gallon pool, baking soda for a 10,000 gallon pool.
Other round sizes
10 ft round pool, 12 ft round pool, 15 ft round pool, 18 ft round pool, 24 ft round pool, 27 ft round pool, 30 ft round pool, 33 ft round pool. Or see every size.