Curing new plaster?

[JJParrish]

After having our pool re-plastered in March, the pool guy came out w/ FOUR gals of Muratic Acid. He said he had been told to put in 8 gals, but only had 4 gals on his truck..... Well, we never got the big dust clouds when brushing daily, just small amounts. After the initial 4 gals, we kept adding the acid to keep the ph knocked down, as per instructions. The question is, would the initial start-up w/ 4 gals do any damage to the new plaster??? Or, what are the pros and cons of having a start-up like this? Love this site, Joyce

[JJParrish]

....any and all comments are welcome and appreciated. Thank you. Joyce

[mas985]

Sounds as though he may of did a partial acid start but the objective was the same to minimize the calcium dust. So it sounds as though it was successful.

An acid start is different than a standard chlorine start and bit more complicated. However, to do it properly, you should follow a set of steps which at the end includes raising the PH. So here is what I understand to be a proper acid start.

1) Add enough acid to drive total alkalinity down to 0. 8 Gallons sounds about right for 18,000 gallons but 4 was probably a bit less than needed. PH will drop considerably during this phase. This should be done within a 24 hour period if possible which is why a bunch of acid is added at once.
2) Most if not all of the calcium dust will dissolve during the next couple of days and the surface may soften a bit but should not dissolve so you want to avoid brushing at this step although at light brushing should be ok as well.
3) After 3-4 days, the PH should be up by now but if it isn't add enough borax to bring up to at least 6.8 and start the circulation pumps. Add chlorine as needed. Now you can start brushing.
4) After a week, maintain as normal. Some of the calcium may drop out of solution so you may need to backwash quite a bit over the next few weeks.

Acid starts are generally not a bad way to go but you need to make sure that the PH and alkalinity do not stay low for more than 5 days otherwise the surface may start to dissolve.

[JJParrish]

Thanks for the info, Mark. What does it mean, or what does it look like, or how would we know if/when "calcium may drop out of solution"? BTW, the pool was replastered in MARCH and our water has been kept balanced since about a week or so after the initial acid (ish) start. Also, is it possible for "calcium to drop out of solution" at any time, like now? Thanks, Joyce.

[mas985]

Normally, the calcium stays dissolved in water and the calcium hardness just goes up. But sometimes, if your TA, PH and calcium are on the high end, calcium can start to collect on the floor and/or walls of the pool as scale. If you have not seen it by now, it probably won't be a problem but post your numbers and someone will chime in if anything is off.

[JJParrish]

Thanks Mark. I will get the pool store to check my water tomorrow and then I will come home and use Ben's kit. It will be late afternoon before I can get this done. Thanks again. Joyce