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

By Elizabeth Ireland ; Updated July 21, 2017
A filter that puts dirt back into a pool can be a frustrating part of pool maintenance.
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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.

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.


About the Author


Elizabeth Ireland began writing professionally in 1997 as a reporter and columnist with the "Lancaster (Pa.) Sunday News." She now serves as the marketing and communications manager for Elizabethtown College, where she earned an associate degree in corporate communication. Ireland also covers rock climbing, cycling, the outdoors, home remodeling, relationships, cooking, higher education, fitness and the environment.