CYA and Chlorine levels

greser

Member
Dec 13, 2017
11
Phx, AZ
My CYA was low ~10 days ago (40ppm) so I added 1G liquid conditioner. My Cl- was 9.5 at that time. Now CYA is 50 and Cl- is 12.
My understanding is target CYA is 70 for SWG pool.
If I add more conditioner (Pool calculator recommends 111oz) to get up to 70, will my Cl- continue to rise?

Rest of todays levels: pH 7.6 TA 70 CYA 50 Salt 3600 CH 575 Cl 12 CCl 0.5 Temp 80F

The water looks great, just trying to get it dialed in.
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,173
NY
Hey greser !! Between the UV demand lessening right now and the days getting shorter, your cell will overproduce as the season winds down. Most likely your FC was burning off unnecessarily with the lower CYA and now that it’s higher, you are buffering/protecting the FC and gaining some each day.

What is your pump runtime / swg % ? Had you raised it recently to accommodate FC loss before you realized the CYA was low ? Or did you notice the CYA exactly as the demand decreased recently ?
 

ccbill

Well-known member
Jul 23, 2021
140
Atascadero, Ca
Pool Size
23000
Surface
Plaster
Chlorine
Liquid Chlorine
... will my Cl- continue to rise?
...
As your CYA concentration rises there will be more protection from the sun - less Chlorine will be consumed by the sun. If you leave your salt cell run-time or percentage the same you could see FC rise as you don't need to produce as much chlorine with the added protection.
 

greser

Member
Dec 13, 2017
11
Phx, AZ
My run time is 10p-8a and pool chlorinator is at 45% currently. It has been on this setting for the past 6 months. I added conditioner since I just started my own testing and noted it to be low.
Should I increase CYA to 70 (as recommended for SWG)? Or just leave as is and decrease chlorinator percentage?

Thanks for the advice...
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,173
NY
Running those #s through pool math along with your t-15 claims you should be producing 2.1 FC a day. No idea how you made it through the brutal AZ summer like that but I’m not a look-y the gift horse in the mouth kinda guy. Lol.
Should I increase CYA to 70 (as recommended for SWG)?
If it’s holding now you can let the 50 be. Again, UV demand is on its way down. Be ready to go 70 in the spring though.

Whether you raise it or leave it, the SWG % needs to be turned down when you notice you are producing too much FC. I let mine get to 12 before I cared. It hit 15 by the time I caught it a lot. Lalalalalalalala. Lol.
 

greser

Member
Dec 13, 2017
11
Phx, AZ
Last question… What should the pool chlorinator percentage be?
It’s all starting to click. Slowly but surely. Thanks again
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,173
NY
Around 3 months it starts to degrade and will end up half strength in another 3 months or so. There’s a chart that details the particulars but that’s the basics of it. If the jugs sat out in the sun, either at the store before they made it to the shelf, or at home, it can be weaker in less than 3 months total.

Do you know how to check the date code when you’re buying ? It’s Julian. YY/DDD. As in today is day # DDD of the year. So without googling a chart let’s assume today is day 292 of the year. 9.6 months of 12 times 365 days. Today’s date code would be 21292 and then probably have more #s after it. Anywho finding fresh bottles really helps when possible.
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,173
NY
lied… One more question: Where in pool math does it calculate DC generated by SWG
Ha. Hit the hamburger menu in the upper left corner. Choose effects of adding and then where it says bleach scroll down to SWG. Your T-15 adds 1.47 lbs of chlorine a day. Mess with your runtime and % and the FC expected will tally at the bottom. If you’ve been seeing a loss of 2 FC per day, play with the #s to produce just a hair more. When you notice the FC climbing, turn it down a skootch.

feel free to play with the calculator. It’s awsome. Wanna know what 1 gal of 31% Muriatic acid will do ? Boom. Right there. Or borax / liquid chlorine / 25 others.
 
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