Pool Valve Positions for Skimmers and the Main Drain

Different pool valve positions determine where water flow is directed on the suction side and how much force is used to push water from the pool pump.

Depending on the number of pool skimmers installed or if you have a functioning main drain, they will most likely be connected by a pool valve, specifically a diverter valve.

The diverter valve has a 360-degree rotating handle to close off plumbing ports. Usually, there is an arrow that says “closed” or something similar to show you exactly where it gets shut off.

Various scenarios and situations may force you to close off one port or another to either make repairs or to get higher suction to vacuum the pool.

Let’s break down each pool valve position connected to skimmers or the main drain to understand better how it works when they are open or closed.

Pool Valve is Fully Open

Most likely, this is the position your valves would be in most of the time. This leaves all ports fully open and functioning for full water pressure.

All skimmer ports and the main drain will be sucking in water at the same rates through the pool pump.

Skimmer Ports are Closed

This position will close the suction coming from your skimmer baskets. This leaves the main drain as the only port of suction that’s fully open.

Generally, this position should rarely be used. It can be useful to drain the pool below the skimmers or suck up extra dirt and grime that can be brushed into the drain.

Main Drain Port is Closed

With the main drain port fully closed, this leaves all suction to the skimmers. Not every pool has a functioning main drain, so this is a more common setup.

The main drain should be closed when using a suction-side vacuum cleaner or robot for the pool. This will prevent the vacuum from getting stuck or caught in the vortex of the main drain suction.

This setup can also be used if there is more surface debris than normal. Full suction at the skimmers will push more leaves, sticks, and anything else floating on the top of the water into the skimmer baskets faster.

Pool Pump Port is Closed

Note: this should only be used if your pool pump and equipment are turned off. Leaving the pump on with no water running through is a great way to damage and shorten its lifespan.

This position stops water flowing into the pool pump. Ideally, it should only be used when emptying a pump strainer basket, repairing or replacing equipment, or closing the pool down for the winter months.

A Port is Partially Closed

Valves can also be partially closed, restricting water flow from that port.

You can test this position and see how the pool cleans the water. Restricting the main drain and allowing the skimmers more suction power isn’t uncommon.

Finding the Sweet Spot

There is no right or wrong pool valve position. Test and use what is best for your pool.

If it works having all valves fully open, go for it. If partially closing cleans the surface better, great!

The overall goal is cleanliness so you can go back to what the pool should be about, jumping in and having fun!