OK I am new here and have been reading a lot of great stuff on this site.
Here is my problem. I have a SWG pool 24' above ground 12000 gal that has been great all summer. Now late in the season I have .5 FC and TC 1.5. Water is perfectly clear so you would not think anything is wrong. I went to the pool store to have water tested to make sure my numbers were correct and they said add 2 lbs of shock. So far I have added the 2 lbs and with in two hours back to .5 FC and 1.5 TC (Per drop test). The next day after reading all the things on this board I added 3 lbs of shock. Two hours later same result. So after using the pool calculator I add 2 gal of 6% bleach, same results. Late last night I add another gallon and call it a night. This morning I check and it looks like both numbers mat be closer to 0 so I hope this might have broken the chlorine lock. I have added 8 cups this morning to see if it will hold at 3 FC. If this does not work I don't know what to do next. Do I keep trying to get the free chlorine to 12 to break the lock or do I keep adding bleach to keep it at 3 until it holds?
After the first day of the 2 lbs of shock I did start to get what looked like residue on the bottom of the pool. Also I have a little brown staining on the bottom of the pool, ladder and at the return. It is not something that can easily be scrubbed off so I do not think it is algae. Not sure if it is a result from where I had to add stabilizer to get my CYA back up from zero a couple weeks ago.
12000 gal above ground
I am currently working also to get the phosphates down as of today.