This is a great forum, with tons of information. I just wish I would have found it a few weeks ago. Here is where I am at now, in the process of a drain. But, I'm looking for advice on what to do after the drain.
Here is the story: Lasr season, my pump broke near the end of the year. Spent a few weeks trying to repair, before I just put on a new one. But, the pool suffered as it was fall, and tons of leaves were in at the time of closing now. So those leaves sat all winter (I'm in Chicago area), and the algae was the worst I have ever seen when I had the pool company open.
So, they put in 8 gallons of liquid chlorine at open. When it did nothing at all for the first 3 days, my wife made me add more. Went to the company who installed and opened for me, and they suggested another 12 gallons. I have a 27,000 gallon pool. After another week, no movement. Called them, and they said I may have "chlorine block" and to bring in a water sample. So, I took in a water sample. They told me FC was at 15, Total Chlorine at 15, Alkalinity at only 66, PH at only 6.9, and CYA at 160. They sold me 50 pounds of BioGuard 100 pak, and told me that would get my Alkalinity and PH right, then I should dump in 12 more gallons of liquid Chorine. I spent 3 days putting in that 50 pounds. Checked with a test strip, and PH was still showing low, FC was off the chart of the strip, and the strip showed CYA at over 200.
So, I found this forum, ordered a Taylor pool test kit instead of the strips, and decided to have the water tested again, since I wasn't sure the strips would right with the levels so whacky. Since my pool shop I was going to is a hour drive, I decided to take the water to a local Leslie's for the check. They said they couldn't even read my CYA, because the FC was so high. They said the CYA test should have turned red, and it went yellow because the FC was off the charts. She then put 2/3 drinking water in with 1/3 my pool water, and even that gave a FC reading off her color chart.
So, with my FC apparently nuts, and a CYA that is nuts, I started a drain. But, I have never done that either, and worried I won't do it right. How much water can I drain at once? I have an in-ground pool that has 3 foot steel walls, then some sort of base (I forget what material) and a liner. I have a flat 3 foot shallow end, then sloping down to 8-feet. To drain, I plugged up all my inlets except one, and hooked a hose up to that. Then have my pump running to drain. Do I drain about 2 feet out safely, and make sure I keep water in the shallow end?