Many water pumps are notoriously unreliable. Install a cheap, homemade airlift which will both filter and aerate. Either that or buy a Rio water pump.
I filter a 10-gallon aquarium by airlifting water to a small tote filled with homemade charcoal and the water then drains back to the tank by gravity.
An airline is simply shoved inside a horizontal 1/2 inch pipe to an elbow, which runs a riser to a Tee, just above the height of the tote. From the high T, a pipe juts off to the tote and then elbow down inside the tote. Also from the T, a riser continues up and it simply offgasses. I hope the illustration below helps. The water pumps in burps and makes noise but you can add an attachment to the top of the riser to reduce the noise. See the videos at Olomana Gardens.
You could use a simple on/off timer on your airpump to make timed flood and drain work (standpipe with pee hole/gravel guard in your growbed).
This may not work for a lot of people because of the noise but my aquarium is in a detached garage. Good luck.