U mean no magic fix? Hadn't really given the chemicals much thought as I was looking for no algae when I brush and sparkling water. (I should check FC each evening and add bleach as required to maintain 15?) Yes
So the FC is being used up as it takes care of the algae so if there is a small loss overnite, the algae must be gone....is that the logic? Yes, you've got it
If so then my poor brain is confused because as this algae has bloomed.....my FC was constantly in the 4 to 5 range. No big losses and 0 CC. Just trying to figure out what happened so I can prevent it in the future. I can't answer that. The only variance that bothers me a little is your CYA first testing over 100 (which, if true, could explain your algae bloom)and now 40ppm....you seem to have that pretty well resolved, tho
Also, if shock level stays up until no FC is lost, how does the FC come back down to the normal 3 to 5 level especially if CYA is holding it. The FC will come down typically 2-3ppm daily from the sun....despite that you have CYA in your pool. It doesn't stop the loss, it slows it.
Finally, is it safe to swim at these FC levels? My opinion is absolutely yes.....others are just a little more cautious
I am guessing that temps have something to do with what I am seeing. We have been at or over 100 every day for the past two weeks or so (except a couple of days that were overcast) and the water temp is in the 92 range and the pool gets sun all day until around 7 pm. I apologize again, just trying to ask questions so this makes sense to me. I thought your questions were all very sensible and valid.....you're obtaining a good grasp of what's happening in your pool. I'm sorry I can't explain the algae bloom. I would suggest go forward from here and continue to monitor your pool water