Doing a SLAM when CYA appears to be 0

[al27]

I have been maintaining my pool the TFP way for years and have slammed my pool numerous times. This is the first time that I remember opening to a CYA of 0 though, so I want to make sure I'm doing everything correctly before I start the slam.

PH is 8.0 so I know that I need to decrease it to 7.2 before I start the slam. How long do I need to wait after adding the acid to start the slam? Since CYA is 0, do I add stabilizer to a sock in the skimmer and immediately add enough chlorine to get to 12 ppm, even though CYA is only 0 now? Since I'm going to have to backwash often, will adding CYA to a sock in the skimmer even work? I cannot dangle a CYA-filled sock in front of the return because it is too windy today. Since I will likely lose some CYA when I backwash, should I add an extra amount or should I retest after backwashing and add some more CYA if it is less than 30? I have a feeling that I will have to backwash daily since my pool is a deep green, so I assume that I will lose some CYA in the process. I could buy some liquid conditioner if that would be more effective but it will cost over twice the price.

 

[AndyTN]

The normal response from TFP Experts is to get CYA to 30 before SLAM. Liquid stabilizer will work faster so if you have concerns with the sock method, then just spend a little more to get it done. Your CYA loss during backwash is minimal unless you backwash for an hour. Give it an hour or two with pump running between adding/dissolving CYA, acid to bring down PH, and then bleach for SLAM. Follow the instructions in PoolSchool and check FC levels multiple times per day. Be consistent and diligent to knock it all out quickly.

 

[aeh0603]

You need to wait at least 30 minutes after adding acid before you can add FC. They don't play nice together so you need to make sure the first is mixed in before adding the second.

Before you add CYA, since you are at 0 and presumably had some last year, I recommend doing a quick check for ammonia. Add enough FC to get to 10, let it mix for 15 minutes and check your FC again. If you have more than 5 FC, go ahead and add the CYA and proceed with the SLAM process as usual. If you have less than 5 FC and your CC is high, then you likely have ammonia. Do not add CYA until your FC starts to hold. Keep testing and adding FC to 10 every 10 to 15 minutes until FC holds over 5. Then you can add CYA and proceed with the SLAM process.