I needed to add a gallon of acid to my pool today. I have a 3-4' high tile wall spilling into a surge pond for the pump suction. There was some calcium build up on one section of the tile wall so I poured the acid down the wall to burn off the calcium. I used 14.5% HCL (Muriatic Acid) and now wondering if this is not advised. I flushed the tile afterwards and the acid removed the calcium very nicely. I expect it is probably doing some damage I didn't see. The surge pond is probably about 250 gallons so the pH dropped pretty low in the surge until it was all flushed out. What other damage might I be doing with pouring acid on a tile wall?
Seemed like a good thing at the time.
- Thread starter WardL
- Start date
You'll probably be just fine with that lower % MA, but I sure would have cut it 50/50--brushed it-- and worked my way up from there to be cautious.
- May 23, 2015
- 24,400
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Muriatic acid is a strong acid as opposed to vinegar which is a weak acid. A 10% (9 parts water to 1 part acid) solution of MA has a pH = 1. So it doesn't take much to make a very acidic solution.
Your ceramic tile is probably fine but you need to be careful about grout as it is mostly just cement and cement is easily etched and removed by MA.
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Your ceramic tile is probably fine but you need to be careful about grout as it is mostly just cement and cement is easily etched and removed by MA.
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Actually, a 10:1 dilution of full strength Muriatic Acid (31.45% Hydrochloric Acid) is a pH of 0, not 1. This is because the pH of full-strength Muriatic Acid is -1 so a 10:1 dilution raises this by 1 unit to a pH of 0.
Great ideas! I'll cut the acid with water before pouring on the calcium deposits and scrubbing next time. Thanks!
Is that negative pH a calculation based on the molarity? I would think that the "real" pH might be a bit higher if the H+ ions weren't fully dissociated.
- May 23, 2015
- 24,400
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Chemgeek, as always, is quite right. My original comment was based on faulty math.
HCl is a strong acid with a very large Ka. The assumption that the [H+] = [HCl] is accurate even at very high concentration like what is found in commercial grade HCl. The technical reason is that the chloride ion (Cl-) is an extremely weak conjugate base so all of the protons from the HCl dissociate to form the hydronium ion (H3O+).
So yes, 31.45% HCl has a pH = -1
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