Lowering CYA & TA with Pool Drain

GregorU

Gold Supporter
Apr 5, 2021
1
Dallas, TX
Pool Size
25000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Howdy All,

I have been a TFP member for a week and just received my TF-Pro Salt test kit this weekend.
Test results from earlier today
FC 4.5
CC 0
pH 7.5
CH 275
TA 120
CYA 100
Temp 67 F

I understand to lower my CYA from 100 down to 60 that I will need to drain 40 % of the pool. If I can drain 40% of the pool in under 12 hours and then start filling it back up (fill time less than 12 hrs) for a total of 24 hours for the drain and then fill procedure. Does that damage/hurt the Pebble-Tec if it is not under water? Should I do it a different way?

The TA will decrease with the pool drain? Correct?

I have 40 ft mature pecan trees around my pool and it is shaded over 50% of the time. Could I run my CYA at 60 instead of 70 for a SWG pool? Or is there any real benefit of running a lower CYA in an outdoor shaded pool other than lower FC during SLAM?

Thank you. I wish I would have found TFP after purchasing the house with pool and definitely prior to last years pool remodel. I would be so much further ahead now.

Gregor
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
7,895
NY
Hey Gregor !!!
If I can drain 40% of the pool in under 12 hours and then start filling it back up (fill time less than 12 hrs) for a total of 24 hours for the drain and then fill procedure. Does that damage/hurt the Pebble-Tec if it is not under water? Should I do it a different way?
It shouldn't. Not this early in the season on a shaded lot. You should be ok.
The TA will decrease with the pool drain? Correct
It depends on the fill water. You can test it before and do the math to know where you will end up. You will be sitting around LOTS watching the drain/fill. At some point you will be so bored that math will be fun. Thank me later. 😁
Could I run my CYA at 60 instead of 70 for a SWG pool?
Very possibly but you do still live in TX. So that sun in non shade times can probably still eat more FC than I use all day with no shade. Reccomended levels are just that....... reccomended. Your pool may do fine with a little more or a little less. If you are ever unsure before experimenting, please come here and ask. Just like today. Great job !!!
I have been a TFP member for a week and just received my TF-Pro Salt test kit this weekend.
So how was the kit experience ? Fast service, right ? And a really cool kit too ? We try and tell people but they can never really know until they are well cared for and get to experience the kit in action. After that, they all blindly replace it as needed. I can't think of once that somebody wondered if they should buy the 2nd one when the 1st expired.
 

Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
2,112
Rancho Cucamonga, CA
Newdude's got you covered on most of your concerns. Did you happen do a diluted CYA test? If your CYA tested over 90, it's a good idea to nail down your results. You don't want to drain and refill to find your CYA is still high. Here are instructions from Pool School.

If your CYA level is 90 or higher, repeat the test adjusting the procedure as follows:
  1. Fill the mixing bottle to the lower mark with pool water.
  2. Continue filling the mixing bottle to the upper mark with tap water.
  3. Shake briefly to mix.
  4. Pour off half of the contents of the mixing bottle, so it is again filled to the lower mark.
  5. Continue the test normally from step 2, but multiply the final result by two.
Best of luck!
 
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