Hi mbar - thanks for your input. I did have one more question.

Does it sound like mustard algae - i.e yellowish/brown clouds of fine dust when brushing the pool? I haven't been able to find any pictures online to make me 100% certain that it's what I'm dealing with. I'm only guessing that it's mustard algae since I've never seen it before. Based on your post...I hope it isn't..

Thanks!