sand filter loses sand

[Gyn_Paul]

I have a 9.5 x 4.25 above-ground pool which came supplied with a sand filter not unlike the one detailed below (illustration nicked from an earlier posting by Théière - thanks).

It came supplied with flexi hoses. I have encountered the multi-port valves before but always in bigger installations, where valve was separate from the actual sand filter, and with fixed 50mm plumbing and the waste outlet some distance away from the valve.

It came with no instructions but went together with a degree of common sense (although it's a bit of a bugger setting the pipe in the sand at the right height to ensure it goes in the base of the valve properly once all those lateral pipes are screwed in!), All connected up and leaks stopped with a combinations on PTFE tape and brute force, it works properly in filter mode. However, in backwash mode (and indeed any time the lever is depressed) it pours water and sand out of the waste/drain pipe.

This doesn't seem right to me, anyone any ideas?   Also unlike 5/ on the diag below, mine came with nothing to go on top of the sand. Should it have?

The valve was pre-assembled.

 

p

Link HERE for more information and diagram

[Théière]

Hi Gyn-Paul,

The multiport valves work in the same way as the side mounted version just that the diffuser is built into the bottom of the valve rather than being piped into the diffuser with the side mounted version.

Part 5 is a cover temporarily used to prevent sand entering part 6 whilst filling, it's discarded after the fill.

With regard to sand/water leaving the waste/drain pipe, are you giving sufficient time for the system to depressurise after switching off the pump. The gauge should read 0 before moving the valve.

If sand has got caught in the valve the gasket may have been damaged so a quick check may be in order.