You should figure out how much water will it take to fill your flood table, then it should be fairly easy to find a pump that will do that in any given time.
Most pumps come with a diagram, of how much water it will deliver at what hight.
Then you messure the hight from your reservoir bottom, to the max water lvl in you flow table.
Find a pump that do a little more then what you need, by comparing thouse numbers or just build in a overflow and over size the pump.
All that been said, I am not sure RW is ideal for Ebb n flood.
Im afraid a 10 min soak of a RW cube will leave it too wet, depriving the roots of oxygen and cause slow growth or bigger issues.
RW is better for drip feeding IMO, where hydroton, growrocks and other course medias that drains fast. Are much more suited for ebb n flood, but maybe if it’s a shallow ebb n flood it could work.
Where did you find your inspiration for RW ebb n flood?
I do drip feeding in hydroton pot’s, on simple flow tables that drains back into the reservoir.
1 of 2 Veg cabinets
HPS Room
One side of my new LED closet, 3 tiers of stacked SOG growing.
You can read all about it in my thread, and follow the rest of the build. Of the left side closet, and what else is going on in ‘The Hack Shack’