Although, I do feel for you, I must agree as a life-long cat owner that they are not vindictive and in this situation it usually is because there is something wrong with them. Outdoor Cats usually poop in dirt and cover it up. If they are marking territory they usually spray, not poop. It is possible that may be what he is doing, but unlikely. The benefit of telling the owner is that if he sick (nothing that you should fear, he isn't contagious to humans)they can take him to the vet to get him checked out, since he may not have a litter box at home for them to notice it. Be clear with them that you are telling them out of concern for the animal, not because you are looking to punish him. As for your part of the problem, I too suggest getting a PHEROMONE spray or liquid (available at any pet store) and spraying on the area he poops after cleaning it with a bleach substance to kill the smell and bacteria. They will keep going there if they can smell it and bleach or other cleaners do not get rid of the scent (they can smell it) and making it more uncomfortable. You could put a litter box near by, which could solve the problem, too. But please do tell the owner that their cat may be sick and save both of you from further misery if that is indeed the cause of it.

pH, Alk, and calcium hardness are of particular interest. These look to be calcium stains. If they are,, they won't come off easily or quickly. The numbers asked for will tell a lot. Also test the fill water. Do NOT use strips. Also, if nothing else works, then you may have to try gently sanding the stains with a wet/dry extra fine (220 grit) sand paper. 700 Gallons or 7000? Trucked water is generally municipal water. Now you and others understand why testing your water with a proper test kit is so important. Relying on strips or others telling you it's OK doesn't fly. Homeowners MUST have at least a basic understanding of pool chemistry and why it's important. "Professional" service providers may not be as well versed as they need to be. It's your pool. You need to be. I teach my customers but many/most don't. They want you to depend on them for the mystery for they fear lost business and dependency. That is just nonsense. Scott

I think it's a concrete slab but I need to confirm that (it's an apartment building.) I'm wondering if that's the case... staining from below. I know that the problem with the freezer is that the drain gets blocked and it spills a bunch of water all at once--that I clean up quickly--and then stops. So I don't think there's a plumbing thing, but definitely will need to confirm that before we proceed. Is there a way to remove the stain?

Few Tips for folks building steamers. A. Always choose a real True Porcelain tile. B. Make sure and place the steam head in proper location/direction.. You certainly could have essential oil vapor carried into the glaze of your ceramic It paramount to have the steam head placed propelry and draining Downward. Really need to know more about the build behind the walls. Did the perimeter around the steam head get detailed properly. regards to bleach its never a good idea in a steam/tile shower although it likely didn't ruin the tile glaze in just one spot. especially to the hard right of the head..