A few weeks ago, we had what we thought was mustard algae in the shaded areas of our pool. The pool never failed an OCLT, so we went straight into an MA shock. We kept the FC at MA shock level for more than 24 hours, and during that time, we brushed, had Polaris running, threw all pool floats into the pool and laundered all swimwear. We did not backwash or clean our DE filter because we've only been in the house for about 3 months and have never done that before. We also didn't remove pool lights because they are in full sun areas, and we never saw the mustard algae in those areas. Everything seemed fine after the MA shock.
We're now seeing it again, and I'm now wondering if it could be living in the filter despite the MA-shock-level FC that passed through it for more than a day. I'm planning to do another MA shock, but do we need to clean the filter and replace DE this time? Would we be wise to keep FC at MA shock level for 2-3 days, or is that wasting bleach?
Below are my most recent numbers (TF-100):
CH 770 (previous owner used cal hypo weekly)
Any suggestions are appreciated!