Experience with AA & a couple questions (Sorry for the long post)

mrd5

0
LifeTime Supporter
May 15, 2014
37
Vienna, VA
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.

Couple questions:
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??

Thanks!!
-Mike
 
My understanding is that pH of 6.8 is the lowest the test will show, it could be considerably less (gallon of MA?) My pool math says you quadrupled the proper dosage That should have taken your pH down to about 6.4? That would have required a little over 14 lbs of Soda ash or 455 lbs of borax to get it up up to 7.2. Again, that's my understanding I'll let the experts weigh in on this.
 
I get that the gallon of acid should have only lowered the pH from 7.5 to about 7.0 assuming a starting TA of around 70ppm in a 40k pool. Not sure where timerguy got his numbers though (you can not rely on the Effect of Adding Pool Chemicals section for large pH changes).

I agree that anything below 6.8 may show as 6.8, but I do not understand how it got so low in the first place.

I also get that it would require 8.125 pounds of soda ash to raise from 6.8 to 7.2 with a TA of 60 ... so not sure why you got a different amount.

Disregard, I had Borates set at 50 :hammer:
 
I just plugged it into Pool Math and I must be making some mistake because it's telling me to use 1gal 1cup of MA to drop pH from 7.5 to 6.8 with TA at 60 for a 40Kgal pool -- you scared me when you said I quadrupled the dosage
 
Regardless, it sounds like I must have goofed on my Pool Math entries so I likely just need to add more Soda ash/borax to bring my pH back up.

But, any thoughts on the effectiveness of the AA? Given my old plaster/paint are my expectations too high for all metal staining to disappear given the about of AA I added? -- Again, the stains definitely lightened but they're still noticable.

From reading the AA thread it seemed that people were all pretty happy with the results, so I was kinda expecting everything to clean up.
 
Re: Experience with AA & a couple questions (Sorry for the long post)

That WASN"t from the effects of adding chemicals That was from the recommended dosage after posting the numbers in pool math.

- - - Updated - - -

That WASN"t from the effects of adding chemicals. That was from the recommended dosage after posting the numbers in pool math. Except for the MA addition.
 

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