How much muriatic acid for a 30,000 gallon pool

In a 30,000 gallon pool with alkalinity 80, about 25 fl oz (736 mL) of 31.45% muriatic acid lowers pH from 7.8 to 7.5. Acid demand rises with alkalinity, so use the calculator below with your TA. For alkalinity, 0.6 gal (2.3 L) lowers TA by 10 ppm.

Muriatic acid doses for 30,000 gallons

pH rows assume TA 80, CYA 40 and 77 °F water. Your dose changes with TA: higher TA needs more.
Change	31.45% acid	14.5% acid
pH 7.8 → 7.5	25 fl oz	0.46 gal
pH 8.0 → 7.5	0.28 gal	0.65 gal
pH 8.2 → 7.6	0.27 gal	0.62 gal
pH 7.7 → 7.4	30 fl oz	0.55 gal

Then aerate to bring pH back up. See the alkalinity guide.
Lower alkalinity	31.45% acid	14.5% acid
TA −10 ppm	0.6 gal	1.4 gal
TA −20 ppm	1.2 gal (2 parts)	2.8 gal
TA −30 ppm	1.8 gal (3 parts)	4.2 gal

Run it with your numbers

Add

25fl oz

of Muriatic acid 31.45%

3.1 cups730 mL

Lowers pH from 7.8 to 7.5 in 30,000 gal at TA 80. TA afterwards: about 77 ppm.

Side effects: TA −3.2 ppm.
Never add acid and chlorine together or in the same spot: mixing them releases toxic chlorine gas. Let the first one circulate before adding the other (the wait is shown on each step).
Pour it slowly in front of a return jet with the pump running.
Retest after the water has circulated.

Check the product label. Strengths vary by brand, so enter the % printed on yours. Add one chemical at a time, into the water, and never mix chemicals.

Save this test and get reminded when it is time to retest.

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About muriatic acid

Wear goggles and gloves, open the jug outdoors and stand upwind. With the pump running, pour the acid slowly in front of a return jet, low over the water. Always add acid to water, never water to acid.

Keep each addition to about 0.75 gal in this pool (12.5 ppm of alkalinity), then let it circulate for 30 minutes and retest pH. Bigger single doses can etch plaster and damage equipment near the return.

Never add acid and chlorine at the same time or in the same spot. Mixing them releases chlorine gas.

Dosing a 30,000 gallon pool

In a 30,000 gallon pool doses run to gallons and bags, so pour or broadcast them while walking along the deep end or in front of several returns rather than in one spot. Larger pools take longer to mix: give the pump at least an hour before you retest.

Questions

How much muriatic acid do I add to a 30,000 gallon pool?

To lower pH from 7.8 to 7.5 at TA 80, about 25 fl oz of 31.45% acid. To lower alkalinity by 10 ppm, 0.6 gal.

How long after adding muriatic acid can I swim?

Wait until it has circulated, typically about 30 minutes with the pump running, and retest pH before swimming. Keep children and pets out of the water until pH is back in range.

Is 14.5% acid weaker?

Yes. It is the same acid at about half the strength, so you need roughly twice as much: 1.4 gal lowers TA 10 ppm in 30,000 gallons.