I was initially thinking the same thing, but since I am also thinking of using individual air stones to distribute the Nutes via the Gravity drip system, (aquarium hose to each pot with an air stone on the end) I anticipate the bucket will only serve as a run-off/collector/ Excess root holder.

And if I get the delivery system right balanced with the right amount of H2O/Nutes, I should be able to set this up and monitor w/o all the mess I know I am soon to experience with my Soil Grow.

But to answer your Q.

The Net baskets are 5 Gallons in volume possibly more. (they weren't exactly intended for the use I am concocting)

The Mop Buckets are 3 Gallons or so in Volume. But we will see.