Muriatic acid is hydrochloric acid. Industrial-strength stuff. It will eat metal, fabric, concrete, and your skin if you give it the chance. It is also one of the most useful tools for managing pool pH — and one of the easiest pool chemicals to get wrong.
We're going to walk you through how to dose it correctly, how to handle it without ending up at the urgent care in Waxahachie, and when to call us instead.
Why pH matters in the first place
If your pool's pH is too high (above ~7.8):
Chlorine becomes much less effective. You're paying for sanitizer that isn't sanitizing.
Calcium scale starts forming on plaster, tile, and inside the salt cell.
Water turns cloudy.
Eyes sting.
If pH is too low (below ~7.0):
Plaster starts dissolving. The white "etching" you see on old plaster pools is from years of low pH.
Metal parts in the pump, heater, and ladders corrode.
Vinyl liners get brittle and can tear.
Target pH is 7.4–7.6. That's the range chlorine works best, eyes don't sting, and plaster stays put.
Why pH usually drifts up in Texas pools
A few reasons. Aeration from waterfalls or fountains drives pH up. New plaster sheds calcium hydroxide for the first year. Trichlor tablets are slightly acidic and lower pH, but liquid chlorine is slightly basic and raises it — so liquid-chlorine pools drift up faster.
If your pH creeps up week after week, that's normal. You'll fight it forever. The question isn't whether to use acid — it's how much.
Muriatic acid strengths
Big-box stores carry three strengths. Look at the label:
31.45% (the strong stuff) — common at hardware stores. Most concentrated, fewest fumes per ounce of effect.
22% — sometimes sold as "smoke-reduced" muriatic acid.
14.5% — sold as a "safer" version. Easier to handle, but you need almost twice the volume to get the same pH change.
The calculator handles whichever strength you have. Just pick the right one in the dropdown — getting this wrong is one of the most common dosing mistakes.
How much muriatic acid to add
To lower a 20,000-gallon pool from pH 8.0 to pH 7.4 with a typical alkalinity, you're roughly looking at 24–32 oz of 31.45% muriatic acid. Roughly. Your alkalinity matters a lot — high alkalinity makes pH "stiff" (resistant to change), so you need more acid. Low alkalinity makes pH "swing" and you need less.
The Muriatic Acid Calculator accounts for both your pH and your alkalinity. Don't dose without it.
How to actually do it safely
Read this part twice.
Dose at the deep end with the pump running. This dilutes the acid quickly so it doesn't sit in one spot and etch the bottom.
Pour slowly and low to the water. Pouring from height creates splash and fumes.
Wear chemical-resistant gloves and eye protection. Not gardening gloves. Real ones. Acid eats latex.
Don't lean over the pour. Fumes go up. Your face is up.
Never add acid to a wet pump basket or skimmer. Concentrated acid in low-flow water will damage the equipment.
Never mix muriatic acid with chlorine. Mixing them produces chlorine gas, which is exactly as dangerous as it sounds.
Wait 30 minutes before retesting pH. Acid takes time to circulate.
Wait 4–6 hours before adding any other chemical.
Storage
Muriatic acid corrodes everything around it, even sealed. Keep it:
Outside or in a vented shed, never in the garage attached to the house.
Off concrete (the off-gassing slowly etches concrete).
Away from anything metal — including your pool equipment if at all possible.
Out of reach of kids and pets, obviously.
If your jug looks puffy or the cap is corroded, it's been venting. Replace it.
The dry-acid alternative
Dry acid (sodium bisulfate, sometimes sold as "pH Down") is safer to handle and store. It's also more expensive per pH-point and adds sulfates to your water, which over time can damage plaster and salt cells. We use muriatic acid in the field because it's cleaner long-term. If you really hate handling liquid acid, dry acid is fine for a few months a year — but watch your sulfates.
When to just have us do it
Honest answer: a lot of homeowners shouldn't be handling muriatic acid at all. We're not saying that to upsell. We're saying it because we've seen the burn marks on pool decks and the holes in concrete from spilled acid.
If you're nervous about handling it — or if your pH keeps climbing back to 8.0 a week after you dose it — there's something else going on, and chasing it with acid won't fix it. A weekly service plan from A&M means you never open another bottle of muriatic acid as long as we're on your pool.
Run the Muriatic Acid Calculator or call Thomas directly at (214) 399-7347.
