25,000 gallon pool: how much of each chemical
To raise free chlorine (FC) by 1 ppm in a 25,000-gallon pool, add about 26 fl oz of 12.5% liquid chlorine, 32 fl oz of 10%, or 52 fl oz of 6% bleach.
Always follow your product’s label directions. Pool and spa chlorine, bromine, shock and algaecides are EPA-registered pesticides: use products labeled for pool or spa use, and don’t swim or soak until levels are within the limit on your product’s label. If this page and a label disagree, the label wins.
| Product | +1 ppm FC | +2 ppm FC | +5 ppm FC | +10 ppm FC |
|---|---|---|---|---|
| Pool liquid chlorine 12.5% | 26 fl oz757 mL | 51 fl oz1.51 L | 1.0 gal (128 fl oz)3.79 L | 2.0 gal (256 fl oz)7.57 L |
| Pool liquid chlorine 10% | 32 fl oz946 mL | 64 fl oz1.89 L | 1.25 gal (160 fl oz)4.73 L | 2.5 gal (320 fl oz)9.46 L |
| Household bleach 6% | 52 fl oz1.52 L | 103 fl oz3.05 L | 2.0 gal (258 fl oz)7.62 L | 4.0 gal (515 fl oz)15.24 L |
| Household bleach 8.25% | 36 fl oz1.07 L | 72 fl oz2.14 L | 1.4 gal (181 fl oz)5.36 L | 2.85 gal (362 fl oz)10.72 L |
| Cal-hypo 65% | 5.1 oz146 g | 10.3 oz291 g | 1.6 lb728 g | 3.2 lb1.46 kg |
| Dichlor 56% | 6.0 oz169 g | 11.9 oz338 g | 1.85 lb845 g | 3.75 lb1.69 kg |
| Trichlor 90% | 3.7 oz105 g | 7.4 oz210 g | 1.15 lb526 g | 2.3 lb1.05 kg |
Liquid chlorine percent is the trade percent on pool chlorine jugs; bleach percent is by weight. Cal-hypo adds calcium. Dichlor and trichlor add stabilizer (CYA). To shock, follow the directions on your product’s label.
| Product | Change | Amount |
|---|---|---|
| Baking soda | TA +10 ppm | 3.5 lb1.59 kg |
| Muriatic acid 31.45% | TA −10 ppm | 64 fl oz1.89 L |
| Dry acid 93.2% | TA −10 ppm | 5.35 lb2.43 kg |
| Muriatic acid 31.45% | pH 7.8 → 7.5 (TA 100, CYA 40) | 24 fl oz711 mL |
| Dry acid 93.2% | pH 7.8 → 7.5 (TA 100, CYA 40) | 2.0 lb914 g |
| Soda ash | pH 7.2 → 7.5 (TA 80, CYA 30) | 2.3 lb1.05 kg |
pH doses depend on your TA and CYA, so use the calculator for your numbers. Acid and pH-up amounts are rounded down.
| Product | Change | Amount |
|---|---|---|
| Stabilizer (CYA) | +10 ppm | 2.1 lb946 g |
| Stabilizer (CYA) | 0 → 40 ppm (new fill) | 8.35 lb3.79 kg |
| Calcium chloride 77% | CH +10 ppm | 3.0 lb1.36 kg |
| Calcium chloride 77% | CH +50 ppm (one step) | 15.0 lb6.81 kg |
| Pool salt | 0 → 3,200 ppm (new fill) | 668 lb302.83 kg · 17 × 40 lb bags |
| Pool salt | +500 ppm | 104 lb47.32 kg |
On this page (9 sections)
Quick answer: chlorine for a 25,000 gallon pool (depends on product)
One gallon of 12.5% liquid chlorine raises FC by 5 ppm in this pool, and one gallon of 10% by 4 ppm. From FC 1 to 4 ppm, add about 77 fl oz of 12.5% liquid chlorine (0.6 gallon), 96 fl oz of 10% (0.75 gallon), or 1.2 gallons of 6% bleach. In dry form, about 15.4 oz of 65% cal-hypo (calcium hypochlorite) or 11.1 oz of 90% trichlor. With stabilizer (CYA) at 40 ppm, keep FC at 3–5 ppm.
At this size, weekly use matters more than a single dose. A pool that loses 1 ppm a day uses about 1.4 gallons of 12.5% chlorine a week; one that loses 2 ppm a day, about 2.8 gallons. Sun, heat, and swimmers set that loss, so log a few days of tests before you buy for the season.
Dose table: chlorine by product for +1/+2/+5/+10 ppm
Liquid rows switch to gallons from +5 ppm: 1 gallon of 12.5% or 1.25 gallons of 10%. At +10 ppm, 6% bleach reaches 4 gallons, which is why most owners of pools this size move to pool chlorine or a salt system. Dry products per 1 ppm: about 5.1 oz of cal-hypo, 6 oz of dichlor, and 3.7 oz of trichlor. The liquid chlorine calculator adjusts doses for jugs that have aged.
Shock dose: 2.5 times the label amount
Use the shock amount on your product's label, scaled to 25,000 gallons. That is 2.5 times any "per 10,000 gallons" figure. A liquid chlorine label that says 1 gallon per 10,000 gallons means 2.5 gallons here.
A 1 lb bag of 65% cal-hypo adds only about 3.1 ppm of chlorine (and about 2.2 ppm of calcium) to 25,000 gallons, so one bag is not enough for a label dose at this size. If the label says 1 lb per 10,000 gallons, you need 2.5 lb, two and a half bags. Stay out until chlorine is back at or below the label's swim limit (often 4 ppm). Guide: how to shock a pool.
pH and alkalinity: acid and baking soda
For pH 7.8 to 7.5 at total alkalinity (TA) 100 and CYA 40, the dose is about 24 fl oz of 31.45% muriatic acid or 2 lb of dry acid. At TA 80 it is about 20 fl oz, and at TA 120 about 27 fl oz. Starting at pH 8.0, reaching 7.5 takes about 33 fl oz, which the calculator splits into two additions with a retest in between.
- Lower TA by 10 ppm: about 64 fl oz, half a gallon, of muriatic acid. A full gallon lowers TA by about 20 ppm.
- Raise TA by 10 ppm: about 3.5 lb of baking soda; a +30 ppm step is about 10.5 lb. See baking soda in a pool.
- Raise pH 7.2 to 7.5 (TA 80, CYA 30): about 2.3 lb of soda ash.
For your own numbers: muriatic acid calculator.
Stabilizer, calcium, and salt
- Stabilizer: 2.1 lb per 10 ppm; 8.35 lb from 0 to 40 ppm; about 14.6 lb from 0 to 70 ppm for a salt pool. The stabilizer calculator starts from your reading.
- Calcium chloride (77%): 3 lb per 10 ppm; 15 lb for a +50 ppm step.
- Salt: about 668 lb from 0 to 3,200 ppm. Sixteen 40 lb bags reach about 3,070 ppm; the seventeenth brings you to the target. Each 40 lb bag adds about 190 ppm. See the pool salt calculator.
Pools that hold about 25,000 gallons
None of the above-ground models in our list comes within 15% of this volume, so a 25,000-gallon pool is almost always inground. Estimated from length × width × average depth × 7.48 gallons per cubic foot:
| Size | Depth, shallow → deep | Gallons |
|---|---|---|
| 16 × 36 ft | 3.5 → 8 ft | 24,775 |
| 18 × 36 ft | 3.5 → 6.5 ft | 24,237 |
| 20 × 40 ft | 4 ft throughout | 23,938 |
| 16 × 32 ft | 3.5 → 8 ft | 22,023 |
A deep-end hopper, steps, and benches change the real volume, so treat these as estimates. The 16 × 32 pool page shows how depth changes the total, and the pool volume calculator handles other shapes.
Calculator preset to this volume
The calculator above starts at 25,000 gallons. Enter your estimated volume and readings. It puts the steps in order and splits large acid doses. Nearby sizes: 20,000 gallons and 30,000 gallons.
Safety. Carry and pour one jug at a time, and keep acid and chlorine jugs apart in storage and in the car. Add them at least 30 minutes apart with the pump running. Wear gloves and eye protection. Always follow the product label. Poison Control: 1-800-222-1222.
FAQ
How much chlorine do I put in a 25,000 gallon pool?
About 26 fl oz of 12.5% liquid chlorine, 32 fl oz of 10%, or 52 fl oz of 6% bleach per 1 ppm. One gallon of 12.5% adds 5 ppm. More in how much chlorine to add.
How much shock for a 25,000 gallon pool?
Multiply the "per 10,000 gallons" amount on your shock label by 2.5. A label of 1 lb of cal-hypo per 10,000 gallons becomes 2.5 lb; 1 gallon of liquid chlorine becomes 2.5 gallons. Wait to swim until chlorine drops back to the label's swim limit.
How much muriatic acid for a 25,000 gallon pool?
About 24 fl oz of 31.45% acid for pH 7.8 to 7.5 at TA 100 and CYA 40, and about half a gallon to lower TA by 10 ppm.
Sources
- Taylor Technologies, K-1005 instruction manual and treatment tables: PDF
- Hayward, How much salt to add: hayward.com
- PHTA fact sheet, Sodium hypochlorite: phta.org
- Formulas and reference checks: methodology