ebb flow custom

There is a lot of DIY controllers for an ebb & flow bucket system, as well as commercial controllers. Which do you use? What is best? What is cheapest?

whats up so i just built my own ebb flow with a 18 gallon tub and a smaller tub on top i have the fill and drain setup but my question is that it doesnt fully drain from the small tub is it bad to have the water stuck in the bottom as it does not drain all the way so will mold grow in the...