CYA and start up


LifeTime Supporter
Jun 25, 2013
Bucks County PA
Hi again guys and gals! You have taught me so much and helped us out so much with our pool. Thank You! Another season about to begin!

We took the mesh cover off last week and the pool did not look so bad :) It was a little green but probably the best it has ever been on opening. Unfortunately the pump (Pentair WF-23) would not start. I tried a few things including trying to get the impeller (without taking it apart) to turn, but nothing. I tested the uncirculated water and of course there is no FC. I put in 2 big bottles of liquid chlorine (from the pool store- thanks to you guys I only go in there for this in the Spring at start up) in the pool to try to clean it up while I figured out the pump situation.

I spent all week researching new pumps and I decided that I had nothing to lose by trying to fix it myself. My 16 year old son helped me take the thing apart - some of those bolts must have been machine tightened. We weren't able to get the motor off, but we were able to check out the pump. There were a few really small pine needles in the impeller, but nothing really. I maneuvered the impeller until it was able to spin and put it back together, not expecting anything to work. I said a little prayer and flipped the switch - Hallelujah! It just started humming!!:kim:
Now that the water has circulated here are the numbers:

FC 4.5
CC .5
PH 7.4
TA 70
SALT 2600

I still have some leaves on the bottom of the deep end to scoop out that I will work on

The CYA started at 0 last year when I opened too. We drain about 1/3 of the water when we close and now it is overflowing with all the rain we have had. So I am pretty sure that is an accurate reading.

The pool math says that with my 23000 gallon pool I would need to add 184 oz of stabilizer to bring the CYA up to 60. I was going to put 8 pounds in a sock to start and retest for CYA in two weeks - Does that sound reasonable? I figured I could add more later on - I am afraid of over doing the CYA after everything I have read on here.

Here's the question:
Do I put the stabilizer filled sock in the pool now, or slam the pool first and then put it in? I was hoping I could do it simultaneously.

Thanks! :)


Well-known member
Aug 18, 2015
North Kingstown, RI
Will let someone smarter correct me if needed, but believe the answer is to SLAM first, fix CYA after. Raising CYA first just means you have to use a lot more chlorine, as your SLAM FC value will have to be maintained a lot higher. Cheaper to SLAM at a lower CYA value and then raise when done. But it may be that there's a minimum CYA value you want first, so dunno if leaving at 0 is beneficial...


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

Have you read our instructions on how to SLAM a pool? See this..

Notice that it says when SLAMing it is best to have a CYA of 30 to 40. Without some CYA, the chlorine will burn off too quickly..

You need to add enough CYA to get to 30, but adding more will just make SLAMing harder.. Wait to add the additional CYA until after your pass the SLAM.


Jim R.