I have read the Mustard Algae article in the Solving Problems area of Pool School, wherein it recommends removing the light in order to scrub out the niche, which seems reasonable. I'm guessing without that step any amount of shocking, even at mustard levels, would be wasted effort and money.
Here's my dilemma: That job is pretty far down my priority list by necessity, which brings up the following questions.
1. Is mustard algae a health concern for swimmers, or just an eyesore? If not, I guess I'll just keep brushing it off occasionally until I get time to do the full routine.
2. It's presence has not noticeably increased the FC demand. Is that normal?
3. Although it brushes off readily, I could swear that a faint yellow tinge remains in the plaster where it was. Does MA "embed" itself in the plaster the way black algae does?