I've been using the BBB method for two years and have been very happy. I feel as if I understand the process, perhaps I don't! Our pool is a green mess right now. I added 13 oz.CYA over the weekend to start bringing that level up from what I thought was around 19 (pool store reading using LaMotte fancy tester.) I was surprised at that low of a reading when I had tested and came up with close to 30 but had only about 2/3 the amount of reagent needed. I have refills on order even as we speak! After adding the CYA everything went downhill very quickly. I had been keeping the chlorine at 3-4 since the CYA was low enough. Even after adding 13 oz. that would have brought it up to about 26. That's the backstory
Even though I have started to shock the pool to bring the algae into submission, my FC isn't dropping, any. The sun was off the pool when I started and now it's dark.
I backwashed the filter before I started but wasn't able to rinse because the water level was getting low. Now 2 1/2 hours in, it is still in good shape.
This all brings up a few questions. Why did I develop algae to begin with?? Why isn't the FC dropping and I didn't even show any CC on the last test.
pH should be 7.2 (lowered before I started shocking)