Pool Pump keep running dry? If I run the pump on Recycle, backwash or waste it...

If I run the pump on Recycle, backwash or waste it runs fine for hours.
It singular happens when I set it to Filter and will run dry inwardly an hour or less
I assume I may own a leak somewhere or my filter is clogged?

Inground pool, sand filter

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Answers:    I don`t know an air trickle.not sure why it would run on recycle though unless your sand needs to be replaced...join for pump problems including air leak: http://www.swimming-pool-information.com...

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If it runs dry during operation there is a bleed between pool and pump(pool to pump). If it runs dry when off next the leak could be pool to pump or pump to pool.

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