Dave really sums it up. Not sure why your pool is dragging its tail on the OCLT, but it sounds as if you have been doing everything right. You have no drain, and I think you said before you had nicheness LED lights right? So that just leaves the pool shell (liner).
Without re-reading everything, I suspect this has been said before as well, but be patient and consistent. Start FC testing by grabbing the water sample from the same location, pump running to mix the water well, then using the same FC test process, etc. Hopefully you have a speed/smart stir to help you along. You mention the seams, so be sure there's not one or two of them folded down tightly that you haven't already exposed with a brush. We're rooting for you.
Thanks. Yes, I test at the same location each time (good to know I was doing that right!) and I'm trying to be really exact as I can on my measurements and process. I don't have a speed stir, but based on the quantity of LC and testing reagents I am going through, that isn't in the budget at the moment. I'll check the seams, but it all looks very good and the liner is only 2 years old. The dead algae and dirt always does collect at the seams, though, I'm sure just due to the water circulation. Correct on no drain and nicheless lights. Thanks for the encouragement!
That sure sounds like dead algae which accounts for your overnight chlorine loss. Unfortunately, the SLAM is still not an exact science some pools just take longer than others and we are not sure exactly why. That said, always return to the basic premise.......there are only two things that consume FC in your pool.......UV from the sun and organics. When you do the overnight test, you can be sure that any loss of FC is attributable to organics.
Stay the course. You are slowly getting your pool pristine and you will be rewarded with pristine water. How are you getting dirt in your pool everyday?
Thanks Duraleigh, the dirt and worms just accumulate overnight somehow? I wish I knew how, but every morning I always have to use our pool robot to get the debris out. I mean, it isn't covering the floor or anything, but the pool is typically clear at night and in the morning it has dirt and leaves and worms, etc. We have a yard full of trees and grass and mulch and lots of animals (rabbits, squirrels, moles etc) so perhaps they dig around at night and the breeze blows it in.
Yuck! We certainly have a snake that crawls across our spa cover every night - we see its trail in the mornings. Lots of animals here.
I did just scrub the return jets. They looked perfectly clean and I had brushed them at least a thousand times! But I scrubbed with the magic eraser and clouds of black came off. I feel pretty ridiculous that I thought they were clean. Fingers crossed that they were another culprit and maybe now I’m further along.
Of course now my pump has been off for over an hour. Thinking I need to get started really researching a new pump motor. It was working with just a few 10-15 min auto shut-offs but this is the longest it’s been off. I was hoping to get through this SLAM and then figure out the pump. Guess not! Hoping I don’t regress.
Hallelujah! I think it succeeded! I truly, truly never thought it would. Yesterday morning the FCC was right where I left it! I didn’t quite believe it and so last night I tested at night again and it only dropped .5 overnight. No CC and the pool is clear. There don’t appear to be any piles of algae, just normal dirt. It must have been the return jets.
I can’t thank you all enough for your help and continued encouragement. I’m hopeful I can keep this up! Now I need to research how/when it’s best to test and add LC daily. And to buy a new pool pump motor. Hopefully the rest of the year will be trouble free!
So when to test and add FC-I liked to do it in the late afternoon when the sun was shaded from the pool as it went down. This allowed the FC to do it's thing with the water without the sun taking any of it. I made sure to run the pump for an hour or so after adding the chlorine to make sure it was mixed up good. Just make sure you don't wear any of your work/good clothes when you add the chlorine. No matter how careful I was I always ended up with a polka dot or three somewhere on my clothes