Pumps, filters and equipment
Using a multiport valve correctly
The handle on top of a sand filter sends water in several directions. The wrong position wastes water or pushes dirt back into the pool.
A multiport valve routes water through, around or out of a sand filter. FILTER sends water down through the sand and back to the pool; it is the normal running position. BACKWASH reverses the flow to lift trapped dirt and send it to waste. RINSE runs water the normal way but to waste, resettling the sand so the first dirty water does not return to the pool. WASTE sends water straight out without passing the sand. RECIRCULATE bypasses the sand and returns water to the pool. CLOSED stops flow.
Equipment guides cover servicing and faults on the plant an existing pool already has.
The handle is moved only with the pump switched off. Turning it under pressure tears the rubber gasket inside the valve, and a damaged gasket lets water slip between ports — the usual reason water keeps trickling from the waste pipe in the filter position.
The short version
Pump off before moving the handle
Changing position under pressure damages the internal gasket.
Always rinse after backwash
It settles the sand bed and keeps disturbed dirt out of the pool.
Waste for heavy debris
Vacuuming sand, dust or dead algae to waste keeps it out of the filter.
When each position is used
Filter
Daily running and normal vacuuming of light debris.
Backwash, then rinse
When the pressure gauge has risen noticeably above the reading recorded after the last clean backwash.
Waste and recirculate
Waste for heavy vacuuming or lowering the level; recirculate to keep water moving if the filter is out of action.
Good habits with a sand filter
Write down the clean pressure
A note on the plant room wall tells everyone when the next backwash is due.
Watch the sight glass
Backwash until the water in the glass runs clear, then rinse briefly.
Finish on filter
Check the handle is back on filter before leaving the plant room.
Common questions
Why does water run to waste in filter mode?
Usually a worn or torn spider gasket inside the valve, often from moving the handle with the pump running.
How long should a backwash last?
Until the sight glass runs clear, followed by a short rinse. Over-long backwashing wastes water and salt.
Can I vacuum on the filter setting?
For light debris, yes. Heavy sand, dust or algae is better vacuumed to waste.
Related pool care guides
- Replacing the sand in a pool filterA related check on the same part of the plant.
- Cleaning a pool cartridge filterA related check on the same part of the plant.
- Backwashing a sand filterA routine task that prevents the same trouble.
- When pool pH is too highAnother water problem with a related cause.
This guide sits under pump & filter services. Browse all pool care guides. We look after pools at homes and commercial properties across Dubai.
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