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Why Is My Pool Filter Putting Dirt Back Into the Pool?

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Pool maintenance is a necessary evil if you want to lounge in clean, cool water on a sweltering summer day. It’s frustrating to find that your pump is putting dirt back in after cleaning. The problem could be as simple as a faulty valve.

Small Sand

The sand in your filter might be too fine and is passing through your filter and into the pool. Sand that is at least .45 to .55 mm is required for most sand filters.

Old Sand

The sand in your filter might be old and needs to be replaced. As sand breaks down, it becomes finer and can pass through the filter.

  • Pool maintenance is a necessary evil if you want to lounge in clean, cool water on a sweltering summer day.
  • The sand in your filter might be too fine and is passing through your filter and into the pool.

Broken Lateral

A lateral – one of the small tubes in the bottom of your filter – could be cracked, allowing sand to pass through it.

Malfunctioning Valve

The filter control valve might be malfunctioning, notes Eco Pools. Multiport valves, if worn or if the gasket is slipping, allow the water being pulled from the swimming pool to skip over the filter and go directly back into the pool without being filtered.

Oversized Pump

Your pump might be too large for the size pool you have. If the pump is too large, it will push the water too hard through the filter, pulling dirt with it.

Backflush A Pool Filter

There should be a power switch near the pool pump outdoors in a weatherproof housing, or in the pool house. A push-pull valve sits on top of a vertical PVC pipe connected to the side of the filter. If you have a multiport filter, one that has several filter choices on top of the filter, push down on the multiport valve filter handle and rotate it to the "backwash" position marked on top of the filter. Turn the power on to your pool pump. When the water becomes clear, after about two minutes, turn off the power to the pump. On a multiport filter, push down on the valve handle and rotate it to the "rinse" position.

  • A lateral – one of the small tubes in the bottom of your filter – could be cracked, allowing sand to pass through it.
  • On a multiport filter, push down on the valve handle and rotate it to the "rinse" position.
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