Green opening - pH question

[run53]

I am helping my 84 YO FIL open his pool. As usual it's a green swamp but by using the SLAM process, we can typically get it clean in a week or two. Took cover off Thursday night, started pump and took some readings.

TC=0
CYA = 30
pH = 8.2+ (over the chart)
TA = 40
ch = 120

So, I asked him not to start slam until we get pH down as my understanding is the SLAM will be more effective with a lower pH. Unfortunately, he went ahead and added all his bleach anyways (sometimes he just doesn't understand/listen - old age). So now there is no way for me to get an accurate pH reading as the SLAM has begun.

My question is, can I add Muriatic acid during the SLAM process? I know the pH was at least 8.2 before the SLAM started. According to the pool calculator, I should add 46oz to go from 8.2 to 7.2. I know the pH could be higher than 8.2 but I assume adding the muriatic acid should help, right? Then we could finish the balancing once the TC/FC levels are back to normal.

 

[JasonLion]

I would go ahead and add some acid, but not quite as much as you proposed. Large PH changes are somewhat unpredictable. You don't want to make that large of a change and have it accidentally go further than you want.

There will tend to be several times when the FC level comes down below 10 during the SLAM, especially during the first day. Any time FC is below 10 you can measure the PH and continue adjusting from there.

Lowering the PH will also lower the TA. TA is already too low, so once you get the PH in range, the TA should be increased.

 

[run53]

Thanks Jason.

Maybe I'll start with half the acid (23 oz versus 46 oz)