How to Backwash Your D.E. or Sand Filter With a Slide Valve 

When the pressure gauge is reading 8 - 10 lbs above the clean, starting pressure (after backwashing), it is time to backwash the filter. This process involves turning or pulling/pushing a valve so that the water will flow through the filter backwards, flushing out the dirt and old DE. Hence the name "backwashing." DE and Sand filters can have either a push-pull valve (also known as slide valves) or a multi-port valve (dial-like).

1.  Clean Pool and empty skimmers and pump baskets best that you can.

2.  Shut off pump motor (roll out backwash hose if you have it).

3.  Twist to unlock plunger T-handle, pull/twist plunger upwards until locked (2-3 inches).

4.  Turn pump on.

5.  Watch pressure gauge for backpressure (+ 40 PSI) (and hose for kinks). Be prepared to shut off pump quickly.

6.  Let pump run for 1 minute.

Shut off and push handle back down and lock.

Turn pump on and run in filter position (down) for 15 seconds.

Shut pump off

Twist to unlock plunger T-handle, pull/twist plunger upwards until locked (2-3 inches).

Let pump run for 1 minute

Shut off and push handle back down and lock.

Turn pump on and run in filter position (down) for 15 seconds

Repeat one more time.

Shut pump off

Twist to unlock plunger T-handle, pull/twist plunger upwards until locked (2-3 inches).

Let pump run for 30 seconds

Shut off pump motor and push T-handle back down into locked position.

7.  Turn pump back on and note lower pressure.

8.  Add one-pound D.E. powder per 10 sq ft of filter area. Look on filter tank.

Be gentle but strong with the slide valve. They have a tendency to stick since they sit for long periods of time. When twisting to unlock or lock handle, be careful you don’t break the handle off. Look closely to which way you need to twist it. Some models have unlock or lock with arrows marked or engraved right on the valve. If yours is getting sticky, you might want to lubricate the o-rings with pool silicon to make the slide valve glide better when backwashing.

Important: Make sure slide valve seats all the way down and can lock properly when finished backwashing. One of the biggest reasons for losing water in your pool is an improperly seated slide valve or a damaged o-ring. When it leaks in the slide valve you can’t always see it because it’s in the pipe. Some pool companies put on good site glasses but most do not. So, if you can’t see the water when backwashing, chances are you won’t see if it’s leaking. If you think you it’s leaking, it probably is. Change the o-rings and lubricate really well or call us. We can fix it up for you.

 

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