I'm using pucks right now because my CYA is on the low end (and after 1+ months seems to be holding stable) and supplementing with 8.25% (Home Depot) bleach. I know it's not the reccomended method here, but alas. My filter had been running from 10:30am to 7:30pm every day. I get home around 5:30 and that allows me to test the water and add any chlorine and allow it to circulate a bit if need be.
For the past month the FC has been steady at 4-5ppm every time I checked it and I haven't had to supplement much at all. However, I recently noticed some mustard algae on my mostly shaded walls. We are having a party this weekend so I decided to shock it and get rid of it.
I brushed the yellow algae off, put in some yellow klear (sodium bromide) as directed, and brought the FC up to 15 (using 12.5% car boy). I turned off my chlorinator while do this as I wanted to get the FC back down to normal before the party. This was at about 8:30pm when the sun was almost gone. I tested the water 3 hours later (filter set to run 24/7) and my FC was 15.
8:30am the next morning I checked the FC again and it was still 15. By 3:30pm it was down to 3.5. I added a couple cups at 8.25% and turned the chlorinator back on. My filter was now set back to schedule. Next morning I checked it and the FC was down to 2. I turned the filter on and decided to check it in a few hours. At 12:30 it was down to 1.5ppm. I added a whole jug of 8.25% and at 6:30pm it as already back down to 0.75ppm. I added another entire jug.
It has been hot and sunny all day (upper 80s). My CYA was between 30 and 40 before I shocked it. All other levels (pH CC TA CH) are in normal troublefreepool ranges.
Im thinking that my chlorine has been burning off to drastically low levels during the day since my filter doesn't come on until 10:30am and that's how I started to get mustard algae. And then it comes back up by the time I test it in the evening.