Thanks, very helpful. I'm glad to have options tho there is a definite best (get the darn light out). One more question...if we can get the light out after FC is much lower and we can try to remove while we are in the pool, I'm guessing that I would have to do the mustard algae shock treatment all over again, correct?

Also, based on additional reading, I think the stuff I see around the bottom edges of the pool is probably stains rather than mustard algae.

Many thanks again!