We would wind 1/4" soaker hose, through (drilled holes) in the 4" sewer pipe spacer, I used to separate the 2 buckets. The Thomas pump, I salvaged from E-Bay, used hospital items equipment.
It supplied enormous air flow, through the soaker hose.
Soaker hose makes fantastic bubbles and vapor, rich in nutrients.
Upper bucket full holes all around it, filled with 3 bags of large chunk lava rock, then it had 2 -1/4" tubing that squitter 24/7, IOW’s, 24/7 feeding and 24/7 draining back to sunken reservoir, that was jack hammered into the floor, some 34" away from the grow.