I have a pool with a Paramount Vantage in-floor self-cleaning system installed. The pool is essentially a rectangle, with in-floor nozzles in each corner, one fixed nozzle in the centre of one side, and the drain in the centre of the side opposite the fixed nozzle. The corner nozzles (used to) pop up in sequence and blow water jets across the bottom of the pool - each time they pop up they rotate a little. The fixed nozzle blows a water jet across to the drain.
The system works off my filter pump - the filter is a Hayward sand filter. The pool is salt chlorinated. The return water splits into two - one pipe to the fixed nozzle which is always on (when the filter is running), and the other pipe goes to a Paramount 6-port water valve which distributes the water to the floor corner nozzles (two nozzles are plumbed to two ports each, and the other two nozzles to one port each, so no port is plugged).
The system was installed when the pool was installed about 8 years ago, and worked fine up until about a week ago when I noticed that all floor corner nozzles were up and blowing water. The troubleshooting guide suggests this is due to a lack of water pressure at the distributor valve, and sure enough, when I check the pressure gauge it is at about 20kpa (3psi). The pressure at the filter is 100kpa (15psi). This is a little lower than spec, but it has always run at that pressure - the filter is about 16m (about 50 feet) from the skimmer and distributor valve, and about 2m (6 feet) above water level (the distributor valve is at water level).
All leaf/lint baskets are clean. I have tried the bypassing the filter (set to recirculate), but no change - so the sand is not a problem (have backwashed and cleaned the sand anyway).
What could be the problem? I can't see how the pressure at the distributor valve can be so much less than the pressure at the filter. The salt cell is new (ish - about 5 months old) and is clean. As far as I know, the salt cell is the only thing between the sand and the distributor valve. Since the pipe to the distributor valve is on the downstream side of the sand and salt cell, I can't believe it is blocked in any way - for any debris to make it into that pipe it would have to get through the skimmer basket, the hair/lint basket at the pump, the sand and the salt cell.
Is it possible the distributor valve module (Paramount 6-port valve module) is broken, causing all valve to open thus causing the low pressure?
The pressure gauges at the filter is the same age as the salt cell - about 5 months - and the one at the distributor valve is brand new.
I'm lost - any tips would be very much appreciated.