Pictures later. This appears to be a cast iron floor drain. It has been a problem since first moving in 5 years ago. It has a white "ball" float down in the center, with about a 1" raised rim around the ball. This ball float apparently doesn't work for draining, since I can pour water in, push down the ball, and it doesn't drain. In order to get the floor drain open and have water from the heater/AC or rainwater leakage drain out, I have to unscrew a white plastic drain plug that sits at an angle in the side of the floor drain. (This previously had the AC condenser drain hose drilled into a hole on the top of the plug) ...doing that, of course, lets in all the nastly pooh-gas and often allows the washing mashine to overflow a little bit out the floor drain sometimes. It has been roto-rootered about 2 years ago, and that got rid of all the previous owners ...feminine hygeine products We usually do CuSO4 crystals annually. We're now in a big backup or clogged drain situation. Is repairing a drain like this possible, or will we have to replace the whole thing? There is old evidence in the basement floor of a previous owner cutting out all the concrete in 2 lines from the floor drain to the main stack, and the floor drain to the laundry stack. (a bit like a very wide V-shape with the floor drain at the point, in the center of the basement). Yesterday we began Draino Gell. Waited an hour. Rinsed. Put in enzymes down all drains. Waited 5 hours. Rinsed. Tried enzymes again. Today I will try enzymes again, then consider calling Roto or trying to find a local guy.