I just took over maintenance of my parents 20 x 40 in ground pool. It was essentially a swamp when I started last week but is getting better each day. My father had always added chlorine with stabilized "pucks" so when I started I expected to see his CYA level about 100 or higher. I was shocked to see it did not even register any CYA. I filled the sight tube to the top of the tube with test solution and the black dot is still perfectly clear. I've checked it twice with the same result. I'm adding about four gallons of 8.25% bleach daily only to find the FC down to about 1.0 to 1.5 ppm the next day. I initially added two Trichlor pucks in each of the two skimmers then two days ago increased it to six in each but the CYA level has not yet increased. I'm thinking I need to add some CYA to get the level up to at least 20 to 30, then continue to use the Trichlor pucks and monitor the CYA level until it reaches about 45 before switching to chlorine bleach.
Am I doing the right thing by adding CYA. The local pool store has it in solid form and is suggesting adding an eleven pound bag. Any advise on how to go about adding it. I did see these instructions on this site.... "Solid stabilizer can take up to a week to fully register on the test, so don't retest your CYA level for a week after adding some. Solid stabilizer is best added by placing it in a sock in the skimmer basket. The pump should be run for 24 hours after adding solid stabilizer and you should avoid backwashing/cleaning the filter for a week."
Also the other test readings were way out as well. The TA was at 10 so today I added all the baking soda I had on hand. I added four 4 lb boxes which raised the TA to 40. I'll get some more for tomorrow. The pool has a vinyl liner so I want to get the TA up to 100 - 120. The PH is at 6.0 so I'll be adding borax but I think I remember reading not to do add borax and baking soda at the same time, so I'll do that later. The CH is at 200 but I'm not concerned with that. Like I said the pool has come a long way to recovery but I'm a little nervous about adding too much CYA and then have to do water replacement. Any advise would be appreciated. I should also note that the pool is an older pool (1975) and uses a Hayward sand filter.