Hello, first post in this great forum and I've been reading around and learning a lot for about a week. Moved into house with pool 2 years ago. The main drain has never worked and I believe it is connected to the skimmer. I ran a hose down the main drain line and it stops at about 3 feet. I could see water coming up from the main drain when I turned on hose. At the pump I have a diverter valve which opens and closes a side wall input (for auto vacuum) and the skimmer. There is no float valve in the bottom of the skimmer. I was wondering if anyone knew what kind of skimmer I have and what I need to make the main drain work in conjunction with the skimmer. Also are the float valves universal? I have attached a photo of the skimmer floor. The left hole goes to the pump and the right to the main drain. There are two raised nubs on the skimmer floor as seen on the bottom of the photo. Also a center hole. Any help would be appreciated.