I noticed I've been battling pink slime (biguanide pool) for the past few weeks. It always collected at the same place on the deep end wall and in and around the seat. I'd brush it but it always came back again within days. I know I should have addressed the problem further before closing but it just wasn't feasible since I was busy trying to get rid of some unknown discoloration that cropped up over the past few weeks on my granite coping. And before that I battled efflorescence or calcium deposits on the tiles. Both issues were pretty well ameliorated with acid magic. But regarding tackling the pink slime, things got difficult lately since I broke my foot right before closing the pool, my mom went in the hospital with a stroke, and our dog contracted a clostridium infection. Tough couple of weeks. So, I have no idea if that stuff will continue to grow over the winter or not, but next year I think my last chance at keeping a biguanide pool going is to try these aqua finesse tablets. If that doesn't work, I think I will need to concede defeat and convert to chlorine. And yet despite the presence of slime, the water looked absolutely beautiful. At any rate, any thoughts on closing with that gunk in the lines would be appreciated. Quite possibly I have often closed with slime or mold in the lines and may have never realized it. I'll probably have to pull back the cover again several times during the off-season to adjust the pH. For whatever reason, it still is going up even though the new plaster is now a bit over a year old. So it will give me a chance, depending on water clarity, to see if the slime issue gets any worse. Hopefully the colder water temps will keep things in check until next spring.