Add Cya before SLAM?

[Windylou]

At closing last year, cover ripped and we just left it so I knew opening was going to be a challenge. Went to open last weekend & pump was shot, so had to order a new one. It came in, so we’re hoping to get opened today. Cya test is showing less than 20. We could still see the dot with the tube full, my suspicion is that cya is zero. Chlorine of course is zero. Do I need to add cya before starting slam? My understanding is that the lower cya is, the less chlorine you need to reach slam. Also ph is over 8.4, is it muriatic acid that lowers ph?

 

[JJ_Tex]

Muratic acid to lower the pH and get your CYA to 30 to protect your FC from the sun, even during a SLAM.

 

[Windylou]

Thanks, any idea how much muriatic?

 

[IceShadow]

Depends on your pool size, TA, and pH. Put those into pool math and it will tell you. I recommend doing half, letting it circulate for 30 mins, then testing and re-checking the remaining amount to be sure you don’t overshoot.

 

[aeh0603]

If you haven't added the CYA yet you might want to do a quick check for ammonia first (if you already started and your water holds FC you can skip this)

Add enough liquid FC to get to 10. Mix well, check FC level after 20 to 30 minutes. If FC is over 5 you may proceed with adding CYA and follow the normal SLAM process.
If FC is less than 5 and CC is high, this indicates you likely have ammonia in your water. If this is the case do NOT add CYA (and remove any dissolving in a sock) until you get rid of the ammonia! To get rid of the ammonia continue testing and dosing your FC to 10 every 10 to 15 minutes until FC holds over 5. At that point you can resume adding CYA and follow the normal SLAM process.