How much chlorine for a 15,000 gallon pool?
Raising a 15,000 gallon pool from 1 ppm to 4 ppm takes about 46.1 fl oz (1.4 qt) of 12.5% liquid chlorine, which leaves about 4.9 ppm of salt behind once it is used up.
How to work it out
- In short: work out how much chlorine the rise takes for your pool’s size, then how much of your product contains that much.
- Rise: 4 − 1 = 3 ppm
- 3 ppm × 56,781 L (15,000 gal) = 170.3 g of chlorine (1 ppm = 1 mg per litre)
- 170.3 g ÷ 125 g per litre (12.5%) = 1.363 L = 46.1 fl oz (1.4 qt)
Fifteen thousand gallons is a big above-ground pool (a 24 ft round holds about 13,000) or a mid-size inground pool. At this size the product you choose for daily chlorine matters more than the dose itself, because the stabilized products keep adding cyanuric acid every day you use them.
Adjust for your project
- Free chlorine rise
- 3 ppm
- Label-style rate
- 10.2 fl oz (1.3 cups) per 10,000 gal per 1 ppm
- Salt it leaves behind
- 4.9 ppm
- Liquid chlorine labelled 12.5% “by weight” is a little stronger per ounce than 12.5 trade percent (about 14 g of chlorine per 100 ml instead of 12.5), and every jug loses strength as it ages. Either way, retest after it circulates.
15,000 gallons, 1 → 4 ppm, by product
| Product | Add this much | Stabilizer (CYA) this adds | Calcium hardness this adds |
|---|---|---|---|
| liquid chlorine | 46.1 fl oz (1.4 qt) | 0 ppm | 0 ppm |
| bleach | 96 fl oz (3 qt) | 0 ppm | 0 ppm |
| cal-hypo | 9.2 oz | 0 ppm | 2.1 ppm |
| dichlor | 10.7 oz | 2.7 ppm | 0 ppm |
| trichlor | 6.7 oz | 1.8 ppm | 0 ppm |
Where stabilizer creeps in
A 3 ppm daily rise in 15,000 gallons is about 46 fl oz of 12.5% liquid chlorine — a gallon every two to three days. The same chlorine from dichlor would be roughly 10.8 oz a day and would add about 2.7 ppm of CYA each time. Over four weeks that is about 76 ppm of stabilizer, enough to push a pool that started at 30 ppm past the 90 ppm the Model Aquatic Health Code allows in public pools.
- Liquid chlorine: the CYA doesn’t move. Salt rises about 5 ppm a day — trivial, and useful if you run a salt cell.
- Trichlor tablets: about 0.6 ppm CYA per ppm chlorine, so a 3 ppm-a-day habit adds roughly 1.8 ppm of CYA a day. See how many chlorine tablets for a 20,000 gallon pool for the weekly math.
- Cal-hypo: about 2 ppm of calcium a day instead. Fine for soft water, a scale risk in hard-water areas.
- A common mix: stabilized chlorine at opening to build CYA to 30–50 ppm, then liquid chlorine (or a salt cell) for the rest of the season.
Doses for neighbouring sizes: how much chlorine for a 10,000 gallon pool and how much chlorine for a 20,000 gallon pool. Need to find your volume first? A 24 ft round pool is worked through in how many gallons in a 24 ft round pool.
Different size? Use the full Pool Chlorine Calculator.
What you’ll need
- Liquid pool chlorine (sodium hypochlorite)Budget price
Adds chlorine without stabilizer or calcium. Strength is printed on the label — commonly 10% or 12.5% — and it weakens with age and heat, so buy it fresh.
See options on Amazon (opens in a new tab) - FAS-DPD drop test kit (chlorine, pH, TA, CH, CYA)Mid-range price
A drop-count kit reads free chlorine to 0.5 ppm (or 0.2 ppm), plus pH, alkalinity, calcium and stabilizer. Every dose on this site starts from a test, so this is the one thing worth buying first.
See options on Amazon (opens in a new tab) - Stabilizer / conditioner (cyanuric acid)Budget price
Shields chlorine from sunlight. Dissolves slowly — follow the label (many say a skimmer or a sock), and don’t backwash for a few days.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How much bleach raises a 15,000 gallon pool from 1 to 4 ppm?
About 96 fl oz (3 qt) of 6% plain bleach.
How much dichlor for a 15,000 gallon pool to add 3 ppm?
About 10.7 oz of 56% dichlor, which also adds about 2.7 ppm of CYA.
Other common sizes
- How much chlorine for a 10,000 gallon pool — 30.7 fl oz (3.8 cups)
- How much chlorine for a 20,000 gallon pool — 61.4 fl oz (1.9 qt)
Sources
- CDC Healthy Swimming — Home pool and hot tub water treatment and testing (opens in a new tab) — pH 7.0–7.8; free chlorine at least 1 ppm in pools (2 ppm with cyanuric acid) and 3 ppm in hot tubs; no CYA in hot tubs; test twice a day.
- CDC — Model Aquatic Health Code, 5th edition (2024), code (opens in a new tab) — Free chlorine minimum 1.0 ppm (2.0 with CYA, 3.0 in spas); pH 7.0–7.8; CYA at or below 90 ppm; CYA:FC above 45:1 is an imminent hazard; TA 60–180 ppm; turnover tables.
- OxyChem — Soda Bleach Solutions Handbook (re-hosted copy) (opens in a new tab) — Trade percent = grams per litre of available chlorine ÷ 10; weight % NaOCl ≈ 1.05 × weight % available chlorine; strength and specific gravity table.
- HASA — Hasachlor sodium hypochlorite SDS (2026) (opens in a new tab) — Pool liquid chlorine: sodium hypochlorite 12.5% by weight, about 1.2 g/ml.
- Hill Brothers — Sodium hypochlorite 12.5% specifications (opens in a new tab) — 12.5% by weight = 142 g/L available chlorine (14.2 trade percent), 11.9% available chlorine by weight.
- Pool Essentials chlorinating liquid (retail listing) (opens in a new tab) — A 10% sodium hypochlorite pool chlorine.
- US EPA label 57787-18 — calcium hypochlorite 65% (opens in a new tab) — 65% available chlorine; 2 oz per 10,000 gallons raises chlorine about 1 ppm; superchlorinate with 10 oz per 10,000 gallons.
- US EPA label 1258-161 — HTH calcium hypochlorite 73% (opens in a new tab) — Calcium hypochlorite 73% (70% minimum available chlorine); a 1 lb bag shock-treats 15,000 gallons.
- US EPA reg. 42177-80 — sodium dichlor label (ProPools copy) (opens in a new tab) — Dihydrate, 56% available chlorine; 2–3 oz per 10,000 gallons daily; 1 lb per 10,000 gallons to superchlorinate.
- ICC Building Safety Journal (PHTA Recreational Water Quality Committee) — Trichlor: the dependable pool performer (opens in a new tab) — Trichlor is 90% available chlorine and adds 0.6 ppm cyanuric acid for each ppm of chlorine.
- CDC — Pool chemical injuries press release (2014) (opens in a new tab) — Never mix pool chemicals, especially chlorine products with acid; add chemical to water, never water to chemical.
- CDC — Pool chemical safety: storage poster (opens in a new tab) — Separate acid and chlorine; don’t mix different types of chlorine; keep chemicals cool, dry and in original containers.
- US EPA — Introduction to pesticide labels (opens in a new tab) — Pool sanitizers are registered pesticides; the label is the law.