scrubbing sides of partially drained CYA-ful pool?

christiangavinson

New member
Jun 24, 2021
2
cupertino, ca
I have been dealing with a mistake I made last year. The shock powder, which i thought was Cal-Hypo, was Di-chlor powder.
As a result, my CYA shot to 169 (I wasn't using pucks, so i thought, why bother checking CYA?)
All other numbers are great (FC 4.5-6, ph 7.5, TA 140 (but take off 20 for the CYA's contribution), TDS and hardness all good.)*
*well, turns out that FC isn't so great at my CYA. i get that now. Thus the draining.

Drain 1 got it to 117. this is when i got my TF100, which registered 110-120.
Drain 2 didn't go as far down and got it to 94 at the pool store, and TF100 registered 90-100.
I do have a test bottle of CYA50, so i know what the dot is supposed to look like at a very specific spot on my hip and in my house at a very specific angle.

Currently doing drain 3. was reading about how it can stick to the sides and how fully drained pools can still read CYA from wall seepage.

My question is, can I scrub or wipe those walls (i was thinking just with water and a bit of bleach) and remove that wall CYA? Is it worth it?

Symptoms: never got green, but always seemed to have "powder" at the bottom. Thought i was adding too much DE. Turns out from reading here i'm just slowly killing algae right about as fast as they divide. So i'm probably killing my family (irony content warning: i don't swim)

By the way, All of these numbers are pool store numbers that, after drain 1, are backed up by TF-100 testing. So Totally Anonymous Big Pool Store in Saratoga, CA with your spin test, good on you for getting your CYA test levels right, at least. Their TA has been spot on twice too, and the third was the first test with extreme CYA, so willing to forgive. I don't depend on them, but it's nice to have confirmation that it's not just my eyes getting blurrier.
 
while i was waiting (thanks for the quick reply!), i ran a quick test:

I took two cups of water in a bowl. I used that bowl and a clean rag to scrub about 20 square feet of sidewall.

at the end, the water was DIRRR-TY. but i dipped two brands of test strip and both registered 0 (I have the TF100 CYA test, but didn't want to waste it to find out precisely how zero it was.)

So Mythbusters-confirmed, no detectable CYA on gunnite walls.
 
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