How much Borax to raise pH 0.2 -0.4?

[Mr Bill]

My alkalinity was 150 when tested at the pool store today.

FC 3.0
TC 2.9
pH 7.8
TA 150
CH 150
CYA 80
20,000 Gal IG Vinyl
Water is crystal clear


Added 1 gal muriatic acid, pH now ~7.0-7.2
To get pH to 7.6 how much borax should I add?
Presently trying to aerate with 2 jets pointing up.

[duraleigh]

Bill,

Reread the sticky on lowering alk on this forum:

Dealing with Alkalinity and Calcium

I don't think you want to raise your pH if you're still aerating.

[CarlD]

CYA = 80?
FC= 3.0?
TC = 2.9???? Not possible!
TC = FC + CC always and forever. TC can NEVER be lower than FC.

CYA= 80 means your FC should NEVER go below 5.0.

[Mr Bill]

I had the Cl readings backwards.

Can you explain why increasing CYA requires such high CL levels. The "pool store" doesn't seem to know this at all. What is the chemical basis for this?

[CarlD]

I'll try for the shorty answer:
CYA, or stabilizer, slows down chlorine breakdown. This is really important in the sunlight as UV can break it down in as little as 15 minutes.

So CYA slows down and stretches that time. But there's a catch: It also slows down and inhibits the ability to neutralize contaminants. So you need a higher residual level of chlorine to maintain the same sanitation level.

That's really it in a nutshell. That's why some CYA--generally 30-50ppm is necessary and good, but more is a problem.

HOWEVER---with proper testing (Ben's kit and similar kits) you can compensate for higher CYA with higher residuals of chlorine than are normally measurable in standard kits. Since the chlorine's action has been inhibited, it's no more dangerous to swim in high CYA/High chlorine pools than other pools IF (and only if) both are properly maintained.

That's why I don't like going in any pool but mine: I KNOW how well it's maintained. Of course I'd have no problem jumping in the pools of my fellow PoolForum denizens--unless it's too dang cold (right, Poconos?)

[Mr Bill]

Thanks, Amigo. That was clear. The idea of a 6 ppm of CL still bothers me. I have yet to raise it that high. I have maintained my pool at a 1-3 ppm range for 6 years, but I have had my struggles with cloudiness, algae, etc., alot last year and earlier this year.

I will try to maintain a 3-5 range and see how that work with my 80 CYA. That takes a bag of NaHypo or CaHypo (1 lb) every other night. Does that sound right?