Pool Info: Backwash Valves
DE Filter Push/Pull Valve (Backwash) Position: When the push/pull handle is in the up position, the valve reverses the flow into the filter, allowing the dirty water to go out the waste line or backwash hose.
DE Filter Push/Pull Valve (Filter) Position: When the push/pull handle is in the down position the filter is filtering the water and returning it to the pool.
SAND Filter Push/Pull Valve (Backwash) Position: When the push/pull handle is in the down position the filter reverses the flow through the filter sending the dirt to the waste line or backwash hose.
SAND Filter Push/Pull Valve (Filter) Position: When the push/pull handle is in the up position the filter is filtering the water and returning it to the pool.
Types of Backwash Valves
The push-pull valve, also called a slide valve, mounts to bulkhead fittings on the side of a Sand or D.E. filter. The advantages of a Push-Pull valve are that they are simple to use, simple to understand, have very few parts, and are less restrictive to water flow than the multi-port valve.
Push-Pull Valves use a plunger with two disks (see diagram above). The only action is to either pull the handle up, or push the handle down. Sand filters usually operate in filter mode with the plunger in the up position, and backwash by pushing the handle down (always shut off pump before changing a backwash valve). D.E. filters are usually in filter mode when the plunger is down, and backwash by pulling up on the handle.
When you pull up or push down on the plunger of a push pull valve, you are reversing the direction of water into and out of the filter. This is where we get the word "back-wash", because we are sending the water through the filter backwards.
How Long should I backwash my filter for?
Backwash until the water runs clear out the waste line. Usually about 2 - 3 minutes. You may need to add water to the pool before or after backwashing. On a D.E. filter, the last step is to add the fresh D.E. powder to the filter, through the skimmer. Also effective with D.E. filters is to backwash 2 or 3 times, for a total of 5 mins. Backwash for 2.5 mins, filter for 20 secs, Backwash for 1.5 mins, filter for 20 secs, Backwash for 1 minute, then back to the filter position. This removes more DE powder than just a single backwashing.
When do I need to Backwash?
When the pressure gauge indicates a pressure rise of 8 - 10 lbs above the clean, or start-up pressure, or when flowrate is significantly reduced.
What Maintenance do I need to do for my Slide Valve?
Lubricate the valve o-rings at least once per year. Remove the plunger from the valve body and apply a Teflon based lubricant like Magic Lube.
Help! My Slide Valve leaks out the waste line all the time!?!
You most likely have "blown a gasket". Remove the plunger from the valve body and inspect for broken or missing disc o-rings.
The multiport valve, also called MPV valves, mounts on to bulkhead fittings on the side of a Sand or D.E. filter. Many sand filters use a top mounted multiport valve, located on the top center of the filter tank. The advantages of a Multiport valve are that they have, well, multiple ports. This allows for more options than simply Filter or Backwash.