I am also new to this forum and rehabbing a true foreclosure swamp. I think I've seen elsewhere reference to starting shocking before adding cya -- I know I did, just to start knocking down the smell enough to even work on the pool, which had a rancid, anaerobic smell on opening. I am now about to add a little cya b/c mine is below 20. I am also working semi blind while waiting for my test kit to arrive. I think the working theory is that it's all a moving target until you have a firm lock on what's in there, so testing now would be useful because I believe you need an effective TA level to get true reads on the ph, and that for shock to work, you also want the ph to be more or less stable.
Adjusting TA affects the pH level but it is not nessesary to adjust TA before shocking. You do want the pH to be between 7.2-7.5 before you begin the shock process as high levels of FC (>10 ppm) will cause a temporary rise in pH. When the shock process is complete and the FC has fallen into the normal operating range, the pH will drop back to pre-shock levels.The cya, as far as I can tell, is germane to know what FC target to hit in order to be in true shock mode and sustain it.
This is correct. It is important to know the CYA level prior to beginning the shock process. If the CYA is over 50 it is best to drop it into the 20-50 range by doing a partial drain and refill. If the CYA is 0-20 it is best to raise it to 20 during the shock process and then raise it to the recommended level of 30-50 (70 if you use a SWG) after the shock process is completed.
Again, the caveat is that I'm a total newbie myself, so hopefully someone with adequate experience will confirm, correct or clarify (pun intended.) however, since I'm a few steps further along on my swamp, I'm happy to share whatever errors or triumphs I encounter along the way
best wishes in your reclaimation!
