How do you determine the size of res you need for a ebb and flow?

Currently im looking at 3Lx2Wx8"H


wondering what kind of res is needed for this?

How many plants?

4 per square foot, so 24 at most

i have the same question, say 4 per square foot, on a 4x4

I'd say you'll need at least a 20 gallon resevoir.