This may be long but want to give all pertinent info, so try to bare with me:
After opening my pool this season, I quickly discovered that my Salt cell has ran it's life expectancy. BUT before I knew it was bad, the salt was reading too low according to the automated board for the SWG to work (which I expected as I drop about 8" of the water for the winter and then refill for the spring). So I added 5 bags (200lbs) of salt. The board was reading only 2600 after. Still too low for the system to work. I thought: "Wow. I must have dropped more water than I thought prior to closing". So I added another 5 bags which would be the correct calculation to go from 2600 - 3200. At this point my cell was reading only 2800. High enough for it to kick on and actually produce chlorine. But clearly inaccurate according to hand calculations. At this point I manually tested the salt. One test showed 4500, another 4000. Based on what I typically know I need to add and what I actually did, I think the 4500 is more accurate.
So I brought the cell to Leslies and had it checked out - It failed. I ordered a new cell, which should be here Tomorrow..... In the meantime I had some water adjusting to do. Because when the new cell gets here and hopefully reads proper, it will not work if it is reading too high of salt. So I dumped water. LOTS of it. Luckily I had yet to bring my Calcium and CYA back to proper levels. If I did I would have just dumped them in the woods too. So out with about 10" of high salt water and in with new fresh water. Obviously, the bad SWG was producing no Cl at this time, so I dumped a gallon of 8.3% bleach into pool while filling back up on Sunday. (if you are still with me, thanks)
Monday early afternoon: Pool high enough to get the skimmers going, so I started the CYA in sock routine. But only added 1/3 of what I needed to get to required amount. I also dumped a gallon of bleach in for good measure.
Monday night: Pool now full, I checked FC levels - it was 5.0. Sounds about right as Monday was somewhat cloudy. But I really didn't have much CYA dissolved either at this point. Added another 1/3 of my CYA to socks and let pump run. no more bleach.
Now for the bizarre part:
Tues night: First I checked my CYA socks. Contents were fully dissolved. GREAT - I'm getting there. Next I checked FC again. 5.0. Sucker was still holding after another day of full sun, no more bleach, and only about 2/3 the CYA added. At this point I added the remainder CYA to the socks but no more bleach.
Wed night (Last night) I checked the socks. CYA was fully dissolved. So I figure time to test it. Now I hate this CYA test. I feel it is extremely inaccurate and totally subjective as to when that lousy dot actually disappears. It was dusk unfortunately, so not the best of conditions to test in. I tried under a few different lights and can conclude it is definitely greater than 50 but less than 80. (I want to target 70). Anyway, close enough for now till I can try again in the sun.
Other results from last night:
pH = 7.2
TA = 70
FC = 5.0 (maybe a tad less, but certainly not 3.0) Call it 4.0. Either way I cannot believe how well this pool has held CL for over 2 days (55 hours) of no bleach dosing, of which the first day had virtually no CYA to speak of yet.
What's your guys' take on all of this?