[quote=montsnmags;447153]Aye, I sort-of felt the same about it, though I've seen it referred to as "natural" as its some kind of "biofilm" (what, like blue-green algae?). Mostly we don't use it because, well, the spa easily takes the blanket, and the pool is enough buggerising around with without adding more chemicals to it.
I dunno about "natural," but it really never hurt Tim to accidentally get squirted with it. His wife never squirted it into his eyes, however, just in case. And because she knows payback is a beeyotch. 
Right now, we're "chelating" brown stains on the bottom.
Drink plenty of water and cranberry juice, and see a urologist. 