Having never replaced a toilet before, I had some questions in the midst of a bathroom remodel. As part of our remodel, we're replacing the toilet, but we're also planning to lay down tile in place of the vinyl flooring that was there. We have concrete slab subfloors and so we'll tile directly on top of that. Originally, I assumed I would just tile around the existing flange and then use closet flange extenders to get up to the proper height. But the consensus online seems to be that for a better fit, it's best to install the flange on top of the finished floor. So... after demoing the bathroom and removing the old toilet, I discovered what looks to me like a cast iron flange nailed into the concrete. It's fairly corroded and some of the concrete around it is crumbling. Our condo was built in 1973 (we only just moved in a little over a year ago) and I'm not sure anyone's ever replaced the toilet before. Needless to say this wasn't what I was expecting to find. I was expecting a fairly standard flange, like the kind you see in all the home improvement books. :D So I stuck a pry bar under the flange to see how much give there was and whether it could be easily removed and when I pulled up, not only did the flange move but the pipe below seemed to move as well. There's so much rust/corrosion build up that it almost seems as if it's one piece. I stopped immediately for fear of busting something and creating a huge headache for myself (and my downstairs neighbor). I have a plumber coming next week to move some of the plumbing around so we can install a pedestal sink so I'll probably just ask him then as well, but in the meantime, I was curious if anyone has seen this before and what is the best way to proceed both in terms of flange replacement and preparing for tile and toilet installation. My first thought was just to put a super ring on top of the old one and then build it up to the height of the tile with extenders. But again, I'd like the best fit so maybe I do need to remove the old flange. Thoughts? I'm not all that knowledgable about or comfortable with plumbing so any help would be greatly appreciated.

My main drain line is on side of the house, and I have kitchen sink and washroom on the other side. And I have slow drain problems. At first I tried a liquid. After a few days I still notice the wash room sink slow draining and filling up from the draining kitchen sink. So I tried that CLR Pressure, and sealed all drains, to have black stuff come flying out the vent pipe on the roof. So I think I have bad blockage in the line after the vent... Also walnuts flew out of pipe... Squirrels!!! Suggestions? Plumber? Thanks Kmax