This will be a basement grow. I will have to dig a pit for the nute reservoir so that it is lower than the trays. The trays will be on a pallet, which will be on the ground. I'm doing 3 (or 5) cuz I'm concerned about having to empty (and refill) so many tubs. Small tubs means less water is required. I plan to get another pump and attach it to a LONG hose so that I can just drop it in and send everything out to the lawn, without having to maneuver a 25 gallon bucket around.

Plus, those mortar trays are only $10 each! I'll spend twice that plumbing the whole thing, but I won't have to worry about maintaining a 100 gallons reservoir. I can fill one of the mortar boxes with 10 gallons, then drain it and fill the next one. A 6x5 ebb-flo tray would require about 40 gallons (guessing). That saves a lot on nutrients and bottled water, right?