You are so close! We just need that CC to come down. Be sure to check the ladder and light niche too. Then read up on this: Pool School - Perform the Overnight FC Loss Test (OCLT)
Are you targeting 24FC in PoolMath? You need to at least aim for that goal or a tad higher. It is all about hitting the FC that will eliminate contaminants and keeping it there so they don't have a chance to survive. 12FC is not high enough.
Didn't realize you had passed the OCLT. Good job!!!
The bubbles are probably from the algaecide you added or maybe also the "ultra cleaner". They should eventually disappear.
I go along the side, halfway between where the deepend slope starts and the deep end wall. I reach out as far as I can and submerge my bottle upside down to at least elbow depth and then invert the bottle. You don't want to be near a return.