My pool sand filter is leaking water from pool thru backwash while filter is running?

Question

My pool sand filter is leaking water from pool thru backwash while filter is running?

Answer 1

like the other answerer said - get the model of your valve and head to your local pool store or call them to make sure they have the parts there.  Probably all you actually need is the diverter gasket, it is the part that closes off the other ports.  If this gasket is torn, stretched or slipped inside then it will not fully close of the ports when you select different options.  The gaskets run anywhere from about $9 and the most expensive ones i've come across are about $30.  To prevent future gasket problems always turn the valve in a clockwise position, never go back and worth between options.

Answer 2

It sounds like you need to rebuild the multi port valve.

Record the make, model number on a piece of paper & go to the pool supply store. They should be able to help you further.

A rebuild is fairly common & an easy fix to do if you are handy.

Good luck.

Answer 3

One of two things here:

1/ The multiport itself, has been warped by an overheat situation. A pump running dry for an extended period can do this for example and so can shutting off the pump if you have a pool heater and the heater was running at pump shut off. The heat travels back to the multiport and deforms it.

2/ The key stem gasket is pooched. That's the gasket the other people are mentioning.  They can tear if you don't turn off your pump when changing the mutiport handle's position or when first starting up in spring, if you didn't leave the multiport handle parked in the winterize position at close or if not marked with one, mid way between  any other position to keep the key stem gasket from sticking to the valve body when sitting there, dry, all winter.

The best thing for you to do is to remove the multiport top after disconnecting the plumbing and take the entire assembly into your pool shop. They can check the valve body and advise on it's condition and they can also fit the new gasket if it needs one, usually in under 20 minutes. The new key stem gasket has to be glued in place. Chances are you don't have the glue needed. They will.

It's also possible that your make and model of filter has the key stem gasket built into the key stem itself and not glued into the multiport body. Rare these days, but some older models were like this. If this is the case, you need to replace the key stem itself, since the parts aren't separate. Again, your pool shop will be the best bet since removing and replacing a key stem takes considerable force and about 4 hands working as one to get the handle pin in and with the handle in the proper position ( not 180 degrees reversed). That spring is stiff.