The skimmers draw water the same way as the main drains, but they suck only from the very top of the pool (the top eighth of an inch, typically). If you do not see a flow of water in the skimmer after trying each adjustment, you may have shut off the main drain and skimmer entirely. I know it works because I can see it suck leaves off the bottom of the pool when I have all the power going to the main drain. Please find listed the very popular range of swimming pool skimmer boxes. Combination Skimmers, or Combo Skimmers, as I like to call them, have the main drain tied into the front hole of the skimmer, on the pool side, and the back hole, or the deck side hole is connected to the pipe that runs back to the pump. No real risk as long as you don't suck hard enough to pull in air, and don't have a deep pool that really needs the main drain to keep circulated. This pool system includes a main drain, one skimmer, a suction port, and a set of return ports. There is a 2″ plug included with each main drain you will use that to plug the bottom hole in each main drain. The Option of Pools without 'Main Drains' Background . So that leaves me with two questions; Is it possible my main drain is intentionally sealed? To install the main drains into a vinyl pool, first remove the cover and face plate off of each main drain pot, and tape over the opening, covering the faceplate screw holes with duct tape. Establish the flow for the main drain and skimmer by shutting off valve B. Skimmer has 2 ports and a diverter plate. Main Drains & Misc. I primarily use a barracuda that connects to one of two holes in the one (and only) skimmer. Have your simmer pump in the drain chamber and the skimmer exit in the fuge to provide oxegenated water to the fudge to help macro metabolize But use the pump setup from diagram 1. Never main drain+skimmer+cleaner all open at the same time. I have a simple in ground setup. Purchased a home with a pool recently and I'm a bit confused as to how the plumbing is setup and if it's working correctly. These are "3-way" style valves. For the first time, in the process of winterizing the inground pool. In this diagram, the main drain is tied into the front port of the skimmer. Instead, it is an outlet, housing a pipe that runs to the pump, which sucks water through a skimmer, then through a filter, then through a heater (if you have one), and then back to the pool via multiple inlets.