PooloraPool chemical chart for a 20,000-gallon pool
Exact amounts for 20,000 gallons of water, for products you can buy at any pool store, in cups, ounces and pounds. Every number comes from the same engine as the Poolora app.
- Raise free chlorine 1 ppm with 10% liquid chlorine: 3.25 cups (26 fl oz · 755 mL).
- Raise alkalinity 10 ppm with baking soda: 2.8 lb (45 oz · 1.25 kg).
- Lower pH from 7.8 to 7.5 (alkalinity 100) with 31.45% muriatic acid: 2.75 cups (22 fl oz · 645 mL).
- Raise salt 1,000 ppm: 166.9 lb (2,671 oz · 75.7 kg).
Is your pool really 20,000 gallons?
A rectangular pool of 34 × 17 ft with an average water depth of 4.5 ft holds about 19,460 gallons. A round above-ground pool 27 ft across with 4.5 ft of water holds about 19,270 gallons. If yours is different, measure it with the pool volume calculator.
Every amount on this page is proportional to volume: a pool 10% bigger needs 10% more of each product. A wrong volume is the most common reason a dose "doesn't work", so it is worth checking once.
Chlorine
How much to add to raise free chlorine (FC) in 20,000 gallons. How high to go depends on your stabilizer and on the swimming range printed on your chlorine label; the chlorine guide explains both.
| Raise FC by | Liquid chlorine 10% | Liquid chlorine 12.5% | Bleach 6% | Bleach 8.25% |
|---|---|---|---|---|
| 1 ppm | 3.25 cups 755 mL | 2.5 cups 605 mL | 5.25 cups 1.25 L | 3.75 cups 875 mL |
| 2 ppm | 6.5 cups 1.5 L | 5 cups 1.2 L | 10.25 cups 2.45 L | 7.5 cups 1.75 L |
| 3 ppm | 9.5 cups 2.25 L | 7.75 cups 1.8 L | 15.5 cups 3.7 L | 11 cups 2.65 L |
| 5 ppm | 1 gal 3.8 L | 12.75 cups 3.05 L | 1.6 gal 6.15 L | 1.2 gal 4.4 L |
Shock to 10 ppm
Raising free chlorine from 2 to 10 ppm, the superchlorination maximum on the chlorine labels we checked:
| Product | Amount |
|---|---|
| Liquid chlorine 10% | 1.6 gal 6.05 L |
| Liquid chlorine 12.5% | 1.3 gal 4.85 L |
| Cal-hypo 65% | 2.1 lb 930 g |
Cal-hypo also adds calcium: this dose raises calcium hardness by about 5.6 ppm. With stabilizer above 25 ppm, 10 ppm of chlorine is not enough to clear algae; see how to fix a green pool.
Lowering pH: muriatic acid
Muriatic acid 31.45% to lower pH from 7.8 to 7.5 in 20,000 gallons (water at 80 °F, calcium 300, stabilizer 40). Higher alkalinity needs more acid:
| Total alkalinity | Muriatic acid 31.45% | Alkalinity after |
|---|---|---|
| 80 ppm | 2.25 cups 540 mL | 76 ppm |
| 100 ppm | 2.75 cups 645 mL | 96 ppm |
| 120 ppm | 3.25 cups 750 mL | 115 ppm |
Alkalinity
Baking soda raises total alkalinity (TA) with little change in pH. Acid lowers it, together with pH.
| Raise TA by | Baking soda |
|---|---|
| 10 ppm | 2.8 lb 1.25 kg |
| 20 ppm | 5.6 lb 2.55 kg |
| 30 ppm | 8.4 lb 3.8 kg |
| Lower TA by 10 ppm with | Amount |
|---|---|
| Muriatic acid 31.45% | 6.5 cups 1.5 L |
| Muriatic acid 14.5% | 15 cups 3.55 L |
| Dry acid (sodium bisulfate) 93% | 4.3 lb 1.95 kg |
Raising pH: soda ash
From pH 7.0 to 7.4 with alkalinity at 80 ppm, 20,000 gallons need about 3.6 lb (58 oz · 1.65 kg) of soda ash (sodium carbonate). Soda ash also raises alkalinity; here it ends near 100 ppm. If alkalinity is already high, aerate instead: fountains and jets pointed up raise pH without adding alkalinity.
Stabilizer, calcium and salt
| Product | Raise by | Amount |
|---|---|---|
| Stabilizer (dry CYA, 100%) | 10 ppm | 1.7 lb 755 g |
| Stabilizer (dry CYA, 100%) | 20 ppm | 3.3 lb 1.5 kg |
| Stabilizer (dry CYA, 100%) | 30 ppm | 5 lb 2.25 kg |
| Calcium chloride 94% | 10 ppm | 2 lb 895 g |
| Calcium chloride 94% | 50 ppm | 9.8 lb 4.45 kg |
| Calcium chloride 94% | 100 ppm | 19.7 lb 8.95 kg |
| Salt (salt systems only) | 250 ppm | 41.7 lb 18.95 kg |
| Salt (salt systems only) | 500 ppm | 83.5 lb 37.85 kg |
| Salt (salt systems only) | 1,000 ppm | 166.9 lb 75.7 kg |
For salt, 167 lb is about 4.2 bags of 40 lb. Stabilizer and salt only come down by replacing water, so add them in steps and retest.
Use the chart safely
- Add one product at a time with the pump running, let it circulate and retest before the next one.
- Acid first, chlorine last, never together, not even in the same bucket.
- These are estimates for typical water; your product label and its limits come first.
- Poolora does this math with your own readings, products and targets, and puts the steps in the right order.
Do it with your own products
Poolora turns your test into the exact amount of the products on your shelf, in cups and ounces, in the right order, and tells you when it's safe to swim. Free to start; every chemical, water balance and history are part of Pro.
Keep going
- Pool chemical chart for a 10,000-gallon pool
- Pool chemical chart for a 15,000-gallon pool
- Pool chemical chart for a 25,000-gallon pool
- Pool chemical chart for a 30,000-gallon pool
- Pool volume calculator
- How much liquid chlorine does a pool need?
- How much bleach to add to a pool
- How much muriatic acid to add to a pool
Sources
- Doses: Poolora engine. Chlorine, alkalinity, stabilizer, calcium and salt by mass balance; pH by a carbonate-equilibrium model with constants from the USGS PHREEQC database
- U.S. EPA registered labels for sodium hypochlorite pool products (Reg. No. 70271-10 and 82357-1): superchlorination 5–10 ppm