CYA and brushing

Good morning all. I joined last week. I have decided to make the switch to BBB as past sanitizing has put me in CYA hell.
I have a 25,000 plaster pool in SE Pennsylvania - 3 years old.
My numbers last week: TH 400 - FC 0 - pH 8 - TA 180 - CYA 150
So far I have added bleach to 20ppm. Added Muriatic acid at different times over a few days totaling approx. 1 gallon all together. I brush every day. Have partially drained the pool 2x (to a total of about 1/3 of volume). We have had heavy rains - this helped to refill. Have also been refilling with house tap (200ppm CH). I have backwashed 1x.
Today's #'s: CH 450 - TC 10 - FC 10 - pH 7.2 - TA 140 - CYA 100.
The problem is that I thought I would see the CH and CYA come down much more by now (CH went up???)
.......am I being impatient?
The question I have for your input is:
1. Could the CH and CYA compounds be in the walls(from past) and am I brushing it all loose?
2. Is it a general rule to shock after heavy rains, or does pool chemistry dictate that?
Thanks in advance for your advice.

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Hi, Smokey,

Question 1 is an interesting thought. I wouldn't think so but that might be a possibility. If that is the case it will diminish quickly, I'm sure.

Question #2 is let your pool chemistry dictate. Once you get balanced out, you may not shock the rest of the Summer. Just test often enough to keep up with it.

If your water looks nice, I would keep doing what you're doing. If your water isn't where you want it to be, bring your Cl up to 25ppm and keep it there 'til it holds pretty close overnight. That would clear up any remaining issues you may have.....except for CYA and CH, of course. Just keep diluting when you can and let the rain help you.

You've done well in "getting it" :) . Now, just keep applying what you know.

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Originally Posted by smokeygrl

Good morning all. I joined last week. I have decided to make the switch to BBB as past sanitizing has put me in CYA hell.
I have a 25,000 plaster pool in SE Pennsylvania - 3 years old.
My numbers last week: TH 400 - FC 0 - pH 8 - TA 180 - CYA 150
Have partially drained the pool 2x (to a total of about 1/3 of volume). We have had heavy rains - this helped to refill. Have also been refilling with house tap (200ppm CH). I have backwashed 1x.

If you have replace 1/3 of the water in your pool with water that has no CYA then you level should have come down from 150 to 100. (1/3 of 150 is 50) so that is an expected result.

Today's #'s: CH 450 - TC 10 - FC 10 - pH 7.2 - TA 140 - CYA 100.
The problem is that I thought I would see the CH and CYA come down much more by now (CH went up???)

You lowered your pH from 8 to 7.2 This and the brushing might have dissolved some scale deposits and caused your CH to rise.
Also don't be surprised if you TA rises if you pH rises. Unless you have airated to drive off carbon dioxide gas you haven't really lowered the TA....just shifted the balance of the carbonate/bicarbonate/carbonic acid buffer system in your water that we all know and love:rolleyes: as Total Alkalinity to less of the carbonates and bicarbonates and more of the carbonic acid which won't show on the TA test. To actually LOWER your TA read this post

http://www.poolforum.com/pf2/showthread.php?t=191

IF your TA does not rise above accepted levels then you probably don't have to mess with it but, IMHO, with a CH of 450 you might be better off getting you TA to about 100-120 ppm. Less of a chance of scaling.

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Hope this helps! Seems like you're doing a great job so far!:)

Waterbear, can I begin to aerate now (with pH at 7.2) or does it only work if I aerate at the same time as I add the Muriatic acid? In other words, do the 2 go hand in hand or is the pH low enough now to get the same result?

Are you planning on running your pool with 100ppm CYA or are you going to be diluting more? If you are going to be diluting I would not worry too much about your TA until you finish that. If you are going to run a higher chlorine level and keep the CYA at 100 then you can start airating now but you will get faster results if you can get the pH to about 7 first.

Okay. Thank you. The plan is to drop the water level down a couple more times and refill - I don't really like the idea of using almost double the bleach to keep the pool clean (with a CYA at 100) so, I'll hold off on aerating. I really appreciate you sharing your knowledge. Take care.

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Originally Posted by smokeygrl

Okay. I really appreciate you sharing your knowledge. Take care.

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That is what this forum is all about! I would imagine that eveyone on here (except maybe Ben) was a newbie once. I myself lurked on this forum for about 2 years reading and learning all I could before I even registered to ask my first question!

You are doing great and seem to have a very good understanding of what is going on in your pool. Welcome to the forum!:)