Going back to salt

parkespapa

Member
Jul 28, 2015
15
Cordova, TN
Have been reading about pool chemistry for salt water pools, and have a couple of questions.

First, here are my test results:

18000 gallons plaster pool in Memphis.

FC: 4.0
CC: 0.04
Ph: 7.6
Alk: 40
Calc: 200
CYa: 20

Just kinda want to know why recommended CYA is so high? 80? To keep SWG at lower rate and make cell last longer? I was going to aim for 50. If I get to 50, what should I aim for with FC?

Why alkalinity so low? Is it because it I get close to 100 I will have to add more acid? (My Ph always tends up)

If
 

cowboycasey

Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
5,931
Southern OK
that is the exact reason for CYA at 80, it keeps the cell use down and just works better... SWG are great at keeping your FC at a level amount, they are not great at raising the FC level unless you are WAY oversized... I have 15k gallons, 3k less than you and I have an SJ45 on mine, I can raise the FC level in the spring and fall easily but the summer I have to run 24/7 for a couple days to do it...

Alk at 40 is low so your ph should not be rising that fast at all unless you have a waterfall or something else aerating your water..

What size SWG are you going with? a 45 to 60 would be a perfect fit for you.. :)
 

Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
1,934
Rancho Cucamonga, CA
Take a glance at your CSI...it's super low with your current numbers, which can lead to plaster etching and pitting. Things will only get worse when you add salt and CYA. You may need to bring up your TA a bit and allow your pH to to rise. Play with the numbers in Pool Math. I got a CSI of around -.50 to -.60 depending on temp and salt level. Check the TA and CH of your fill water. You may want to increase CH up to the recommended level.
 

parkespapa

Member
Jul 28, 2015
15
Cordova, TN
that is the exact reason for CYA at 80, it keeps the cell use down and just works better... SWG are great at keeping your FC at a level amount, they are not great at raising the FC level unless you are WAY oversized... I have 15k gallons, 3k less than you and I have an SJ45 on mine, I can raise the FC level in the spring and fall easily but the summer I have to run 24/7 for a couple days to do it...

Alk at 40 is low so your ph should not be rising that fast at all unless you have a waterfall or something else aerating your water..

What size SWG are you going with? a 45 to 60 would be a perfect fit for you.. :)
I added 4 lbs of baking soda yesterday to get alkalinity up. Aiming for 80.

Am going with Circupool 40.

I do have a waterfall, maybe the reason for Ph running high, also have been using bleach for chlorine, so I guess that doesn’t help.

I was really bad about upkeep last year, and am assuming that’s why my alkalinity and calcium dropped so much. Used to be around 110 and 250.

Am thinking that I need to add calcium, soda and stabilizer gradually until I get to 350, 80 and 80.

My salt tested at pool place at 1200. Should I completely balance water before I add salt, or does it matter?
 

Pool_Medic

In The Industry
Apr 1, 2018
1,451
Bangor Maine
I have tried with cya of 80 and cya of zero.

Difference is at 80 my % is at 10, at 0 it had to be 50-70%.

Remember every cell makes a set amount of chlorine in its lifetime, you can chose to use it all in one year or use it over 4-7.