PooloraHow much bleach to add to a pool
Plain household bleach is the same chemical as pool liquid chlorine, just weaker. Here is how much to add for your pool size, in cups and gallons.
- 15,000 gallons, +1 ppm free chlorine: 4 cups (31 fl oz · 920 mL) of 6% bleach, or 2.75 cups (22 fl oz · 655 mL) of 8.25%.
- Use only plain, unscented bleach.
- How high to go depends on your stabilizer; when you can swim depends on your chlorine label.
Bleach is pool chlorine
Household bleach and pool liquid chlorine are both sodium hypochlorite. Bleach is just less concentrated, so you need more of it. Bleach labels give the strength as % sodium hypochlorite by weight: "regular" is usually 6% and "concentrated" 8.25%. Check yours on the label.
- Buy plain bleach. Scented, "splash-less" and thickened versions contain additives that do not belong in a pool.
- Bleach loses strength as it sits, faster in heat. A fresh bottle matches the chart better than an old one.
Chart: regular bleach (6%)
| Pool size | +1 ppm | +2 ppm | +3 ppm | Shock 2 → 10 ppm |
|---|---|---|---|---|
| 5,000 gal | 10.5 fl oz 305 mL | 2.5 cups 615 mL | 4 cups 920 mL | 10.25 cups 2.45 L |
| 10,000 gal | 2.5 cups 615 mL | 5.25 cups 1.25 L | 7.75 cups 1.85 L | 1.3 gal 4.9 L |
| 15,000 gal | 4 cups 920 mL | 7.75 cups 1.85 L | 11.75 cups 2.75 L | 1.9 gal 7.35 L |
| 20,000 gal | 5.25 cups 1.25 L | 10.25 cups 2.45 L | 15.5 cups 3.7 L | 2.6 gal 9.8 L |
| 25,000 gal | 6.5 cups 1.55 L | 13 cups 3.05 L | 1.2 gal 4.6 L | 3.2 gal 12.25 L |
| 30,000 gal | 7.75 cups 1.85 L | 15.5 cups 3.7 L | 1.5 gal 5.5 L | 3.9 gal 14.7 L |
Chart: concentrated bleach (8.25%)
| Pool size | +1 ppm | +2 ppm | +3 ppm | Shock 2 → 10 ppm |
|---|---|---|---|---|
| 5,000 gal | 7.5 fl oz 220 mL | 15 fl oz 440 mL | 2.75 cups 655 mL | 7.5 cups 1.75 L |
| 10,000 gal | 15 fl oz 440 mL | 3.75 cups 875 mL | 5.5 cups 1.3 L | 14.75 cups 3.5 L |
| 15,000 gal | 2.75 cups 655 mL | 5.5 cups 1.3 L | 8.25 cups 1.95 L | 1.4 gal 5.25 L |
| 20,000 gal | 3.75 cups 875 mL | 7.5 cups 1.75 L | 11 cups 2.65 L | 1.9 gal 7 L |
| 25,000 gal | 4.75 cups 1.1 L | 9.25 cups 2.2 L | 14 cups 3.3 L | 2.3 gal 8.75 L |
| 30,000 gal | 5.5 cups 1.3 L | 11 cups 2.65 L | 1 gal 3.95 L | 2.8 gal 10.5 L |
How much chlorine your pool needs
The right level depends on your stabilizer (CYA), because stabilizer holds on to part of the chlorine. The minimum is about 7.5% of your CYA, and never below 2 ppm when you use stabilizer (CDC):
| Stabilizer (CYA) | Minimum free chlorine | Target range |
|---|---|---|
| 30 ppm | 2.25 ppm | 4–6 ppm |
| 40 ppm | 3 ppm | 5–7 ppm |
| 50 ppm | 3.75 ppm | 6–8 ppm |
Your chlorine label sets the ceiling for swimming, often 3 or 4 ppm. The chlorine guide explains how the two fit together.
How to add it
- With the pump running, pour slowly in front of a return jet. Evening doses last longer than midday ones.
- Never mix bleach with acid or any other chemical, not even in the same bucket. Add chlorine last.
- Keep everyone out while you add it, let it circulate and retest before swimming.
Common questions
Is bleach as good as pool chlorine?
Yes, it is the same chemical. The difference is strength and price per unit of chlorine, so compare the cost of reaching the same ppm, not the price per bottle.
Does bleach raise pH?
A little when you add it, because sodium hypochlorite is alkaline. Most of that comes back as the chlorine is used up. A pH that keeps climbing usually has another cause, like high alkalinity or aeration.
How much bleach to shock a 15,000-gallon pool?
From 2 to 10 ppm: about 1.9 gal (249 fl oz · 7.35 L) of 6% bleach, or 1.4 gal (178 fl oz · 5.25 L) of 8.25%. Ten ppm is the superchlorination maximum on the labels we checked.
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.
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Sources
- U.S. EPA registered labels for sodium hypochlorite pool products (Reg. No. 70271-10 and 82357-1): swimming range and 5–10 ppm superchlorination
- CDC: Home pool and hot tub water treatment and testing (2 ppm minimum with stabilizer)
- Doses: Poolora engine (mass balance by product and strength; pH by a carbonate-equilibrium model with constants from the USGS PHREEQC database)