Based on your description, it sounds like the M53 is ALMOST taking care of the situation, but not quite. IF you have more water than sand, that M53 will handle it.� I would suggest increasing the discharge piping from 1-1/4" to 1-1/2" or even 2". If this doesn't do the job, you might increase to the 1/2HP M98 Zoeller pump with the same 1-1/2" or 2" discharge. The 2" discharge WOULD require an adapter for either pump discharge, but should help.