Hello. My first post. It's long so skip to the bottom for my question if you don't want all the background.
I've had an in-ground pool for about 4 years now. This summer however, I haven't been able to hold any FC. I had been shocking it (though I had no idea what shocking really meant) quite a bit this summer with Bioguard Burnout (pool store recommendation). Even with the old test kit, I could see that my FC was too low. Eventually my pool started to show some algae growth on the walls and bottom that are more in the shadows and at night with the pool light on, we were getting all kinds of water bugs. My wife read online that Inhibit Back-up algicide would kill the algae and bugs. So we dumped in a bunch of this algicide. It didn't help. Though even during this time, the water didn't look too bad, after shocking and brushing it would get brownish cloudy, but I could always see the bottom of the deep end and after a couple of days it would look good again for a few days and then the algae would start showing up again.
Finally the pool store did a Chlorine demand test. They told me to drain my pool to a foot in the shallow end and refill (let the pump run for a while) and repeat and then shock it. I did this, but I still wasn't able to hold any FC. That's when doing some research on how draining the pool was supposed to help I found troublefreepool.
So even though my water never really looked too bad I decided I needed to SLAM my pool, but I didn't have a good FC/CC test kit so I ordered one, but wanted to start the SLAM anyway. At first I thought I was supposed to just add bleach in the morning and at night. I had the pool store check my CYA level before I started and they came back with a reading of 55. I hadn't really known what the CYA level was for before, so I then started going over the readings this summer from the pool store. They were all over the place, one time a 8, so they had me add stabilizer, then it went up to 89, then down to 40 then 55 when I last checked before wanting to SLAM. My FC was 0.5, CC 6.1, pH 7.6 and TA 130. So I made a guess that the 50 was my CYA amount and started the SLAM process on Saturday. So that weekend I added bleach enough bleach to bring FC up to 20 in the evening. Tested in the morning and FC was low and added bleach in the morning again to bring FC to 20. I repeated this every day: Sat, Sun, Mon, Tue, Wed. At first when I would brush the pool, it would always mix up some brownish junk, even after just a couple of hours on Sat/Sun. But by Wed, I could start to see that brushing wasn't mixing up as much stuff.
My Taylor test kit arrived on Wed so I started doing my own testing. FC 0.5, CC 1.5, pH 7.4, CYA 35, TA 135. I repeated the morning and evening shocking to, but to 16 now. But I had also re-read the SLAM process and determined that I was supposed to be trying to keep the FC at shock level each hour. So Saturday, I added 20 gallons of 8.25 Walmart bleach throughout the day when I was home, brushing the pool doesn't seem to stir up anything anymore. But each time the FC level would drop to 1 or 2 at most after a couple of hours. So today (Sunday) I decided to try to shock hourly as I didn't have anything else going on. I retested my CYA and now I think it might be about 35 (maybe didn't do the test quite right the 1st time?) So I've been adding shock all day to bring my FC up to 20 just to be safe. So for my pool that is just over 6 gallons (121 oz) of 8.25 bleach. Each hour when I do the reading again FC is down to 1.5 or 2. I'm 35 gallons in today and Walmart is out of bleach, so I had to go to the pool store to get some more 12.5% shock.
BTW- about by Wed, the pool was looking marvelous darling, crystal clear and my wife says it feels really soft. The vinyl liner feels clean and not slippery for the first time probably since we got the pool.
My question: Is it normal/OK to need this much bleach (35+ gallons in 1 day) and still not be able to hold any FC levels for a crystal clear pool? Is there something else besides algae (and the sun) that is consuming my chlorine?
Thanks for any input!