Damage due to too much Muriatic Acid?

[JFS61]

Had a major kerfuffle this morning, when a family member, mistaking a gallon of Muriatic Acid for a gallon of Chlorine, added the entirety of the former to our pool. I walked out about fifteen or so minutes after it occurred, and wandered why an empty bottle of Muriatic Acid was sitting on the pool deck when I found out what had happened (last time I let anyone else help out on the pool). I immediately backwashed as much water as I could out of the pool, then added what little PH+ we had (maybe a pound or so), and turned the water hose on full (our water has a high pH level) and ran it through the skimmer with the pump going. Fortunately, there was a pool store open, and I picked up some Soda Ash, of which I ended up putting in approximately 5 lbs until I had got the pH stable at 7.5. I added some extra Calcium Increaser to bolster the calcium hardness levels as well. About the only positive I could think of is that our water has a very high alkalinity level (300-400 PPM), so I'm hoping that might have helped by providing a counterbalance to the acid.

Now to the point of my query, just what kind of damage did this do to the pool? It's about 15 years old (needs a resurfacing), and as our water has zero calcium in it, despite best efforts, there have been issues with inadequate calcium hardness levels in the past (prior to my taking over maintenance), so I imagine the walls aren't in the best of condition to begin with.

Is there anything else I should be doing in regards to the chemical levels, or just let it sit until everything rebalances?

Also, are there any visible signs of damage that I should be on the lookout for?

 

[mknauss]

None as long as the acid was mixed in the pool water. You neutralized it pretty quickly and I do not see a heater in your signature (which can be damaged the quickest with low pH water) so no issues.

Using soda ash probably raised your TA pretty high. Check that so you are using the right value in Poolmath.

 

[mgtfp]

First of all, I would cite here the Hitchhiker's guide to the galaxy:

"Don't panic!"

What happened, happened, and I'm sure it happened before. I don't think your plaster will instantly dissolve. The pH might have briefly dipped below 6, but CO2 out-gassing would be very fast at these levels, driving pH up again. And it looks like you brought it already back up to 7.5.

Remember that salad dressing can have a pH of 3. You probably wouldn't store the dressing in a concrete box, but a spilled drop won't immediately burn a hole in the pavers under your dining table.

And most important: Make peace with the person who did that mistake. That person will probably have learnt from that mistake, and I'm sure will be of great help in the future. We all learn from mistakes. That's what makes us human