After the pool went green and stayed there, I drained 90% and refilled, SLAMmed, then started TFP maintenance. Since coming off SLAM, I've kept CYA 40 and the lowest FC was 5.5 since SLAM. CC is 0 or 0.5 every time i test. I have been in the pool and brushing every evening. Brushing ladder steps and sides and underneath, and vacuuming the little holes in the ladder steps to make sure chlorinated water is circulating.
The bottom of my pool has a a section where some mole burrows have collapsed, and otherwise the bottom has some depressions here and there. These depressions and small wrinkles collect what I had thought was pollen - kind of granular looking yellow or green 'grains'. 25% of the pool is directly under a pecan tree. I vacuum those out to waste (or filter), then backflush for several minutes, and rinse. The next morning little pockets return. Two nights ago I put the ladybug in the pool instead of actually brushing. Yesterday morning the bottom of the pool was faint yellow/green along with the usual pockets of yellow-green 'pollen'. It looks like sand, but poofs away with a vacuum or brush.
Last night I dumped the last gallon of 12.5% I had, tested the water 2 hours later and ran out of drops at 21, with the sample still bright pink. I have more drops now, but didn't get to test this AM. I am picking up more 12.5% after work today.
How can I tell for sure this is mustard algae, and if the last SLAM seemed to get rid of it, how will I know it's really gone this time?