Thanks in advance for any information you can provide. Great site, so glad I found it! I read the pool school posts several times and browsed the forum quite a bit. This seems to be a relatively common problem, but would like some specific help. Sorry if this is too long, but want to get as much info out there as possible.
Quick background: I have had an AG pool my entire life. My parents used HTH granular chlorine (added however much every night by dissolving it in a bucket) and nothing else ever for like 20-30 years and never had any pool problems. I installed my pool about 5 years ago and have been using trichlor in a chlorinator (sure wish someone would have told me that it adds CYA!), "shocking" weekly, algecide, etc... thanks pool store! I have not had any major problems, except for very minor green algae spots from time to time, but was always able to control it with "shock." Unfortunately I do not know what any of the levels were when I winterized the pool in the fall.
This year I opened the pool and it was decent looking. I added some water, "shocked" it with the 3 one pound bags like always and all was good. Fired up the filter, filled the chlorinator with trichlor and was set. After like 12 hours of filtering it was crystal clear and beautiful. I tested (strips at the time) and all the levels were within range, except the free chlorine. I turned up the dial in the chlorinator and nothing. Have been to the pool store a few times and everything seems fine except low chlorine. I have had to adjust the PH or alkalinity slightly here and there using backing soda or borax, other than that all was fine. I've tried shocking, bought a new chlorinator, some other non-chlorine shock (potassium, maybe?) and can not get the free chlorine to register on the test strip. I even bought a new bottle of strips in case that was the problem.
About 2 weeks ago (when the 100 degree days started) I was out of town for 5 days. My dad stopped over on the 2nd day to take the filter apart, clean it and recharge with DE because the pressure was starting to rise a bit higher than I liked and I did not have time to get to it. He did that and said everything was fine. I got home 3 days later and the pool literally looked like pea soup. I added more "shock" and filtered / backwashed for about a day and a half and the water was back to crystal clear and beautiful, but still no FC. At this point I was getting tired of the pool store so I google'd the problem and luckily I found this site. I ordered the TF-100 test kit and it arrived yesterday.......
Last night I tested the water at about 9pm (filter had been running for about 2 hours at that point - timer is set for 4 hours in the am and 4 in the pm.) I did each test a few times to make sure I was doing it correct and could get repeatable results and overall I think I was doing everything ok. Results from this test are:
TC: 0.5 (From the Taylor Basic Kit (Blue Box)
TC (Calculated) = 2.5 (not sure why the difference to above TC?)
CYA: >100 (based on the exponential looking scale on the C.A. View Tube I would estimate about 150 - was concerned that this was incorrect so i did this test about 4 times and repeated so assuming its correct. Interestingly, the pool store tested my water on Sunday and told me the CYA was 85!) (EDIT - I forgot about the extended test kit instructions to dilute the sample with tap water and double the reading... will try that tonight and post results.)
Water Temp: 81F
After I tested, I planned to shock the pool to see what happened overnight. I did not have enough bleach to shock to the level required based on CYA (>50 I would assume) so I added about 4.5 gallons of 6% which I thought would get me to FC of about 17. I realize that this would likely not help the situation much, but at least I could get an idea of what was going on. I waited about 30 minutes and tested again:
TC: >5 (From the Taylor Basic Kit (Blue Box)
TC (Calculated) = 20
Water Temp: 81F
This morning I tested again at 5:30 am:
TC: 0 (From the Taylor Basic Kit (Blue Box)
TC (Calculated) = 3.5
Water Temp: 80F
My diagnosis is that I have a mess on my hands even though the water is beautiful and crystal clear! I'm assuming that I need to dump quite a bit of water and refill to get the CYA somewhere in a workable range... probably 1/2 or more of the total volume? Without doing this step first, I would likely need hundreds of gallons of bleach and then would need a ton to maintain as well. Once I get that in range will need to shock it heavy to get rid of the CC, then balance PH, TA, etc. Once I get it in order I assume that will need to add bleach every night as maintenance dose to keep FC in proper range for new CYA level (going to ditch the chlorinator / trichlor except for times when no one will be home to maintain)? Does this seem to sound right, or am I way out in left field?
Thanks for reading this far! Again any help would be greatly appreciated.