So, our pool is about 27 years old and I believe it has the original plaster. Supposedly it was painted 8+ yrs ago rather than being replastered so the surface is marginal at best. There are areas where the paint has come off, some black spots and metal stains on the floor and walls. After confirming there’s metal in the water (.3ppm CU & .8ppm iron) I decided to try the AA treatment. I was pressed for time to get this down so I kinda rushed things and “rounded” my numbers but assumed I was in the ball park. Despite knowing that FC should be 0, I started when it was down to 1.5 (and figured I'd use a little extra AA). The pH was also 7.5. I dumped a gal of MA to bring the pH down -- although a gal was probably a little more than I needed, I assumed as long as I was below 7.2 I’d be ok
I dumped in about 80 oz of Polyquat 60 (again, probably a little more than I needed but figured it couldn’t hurt).
I started with 4lbs of AA (using the ratio of 1lb/10000g) but the change was barely perceptible. Knowing there was some residual FC I went all in and dumped my entire 8lb bucket of AA and lightly scrubbed all surfaces with my ss brush. I also threw a Culator 4.0 in the pump basket for good measure (even though there are mixed reviews on the effectiveness)
Last night (24hrs into the process) I was surprised that while the stains were lighter, it wasn’t 100% effective. I tested the levels and FC=0 as expected, pH=6.8, TA=60.
Assuming that was the best it was gonna look I started to dial the chems back in. I added a gal of Jacks Purple stuff (ouch that stuff is expensive!), a gal of 10% bleach and 7lbs of Soda Ash (recommended dosing by PoolMath). This morning I was really surprised that the pH was still 6.8 after all that soda ash.
1) For the AA treatment, it is less effective if the pH is lower than 7.2?
2) If pH wasn’t the problem, then with a residual FC of 1.5 is double the dose of AA still too little?
3) Why didn’t my pH rise since the Soda ash addition last night? According to PoolMath for my starting pH of 6.8 and TA of 60, I needed 6lbs-15oz of Soda ash for pH of 7.2 The Soda Ash I used was left behind by the previous owner and was slightly “chunky” as if it had seen some humidity. I chopped it up and assumed that wouldn’t make a difference – would it??