I get these 40"x47"x36" plywood boxes from a juice factory for $5.00 each. I cut the shipping boxes into thirds or in half, and add bottoms to the sections as needed. I look for discounted irregular plywood to save money (generally 1/2 price).
To build the basic plywood box would cost about $60 if you used 3/4" plywood at about $25 per sheet. These come banded with heavy metal corners.on a pallet. It's hard to beat these juice boxes built with high grade 3/4" - 5 ply plywood. It takes about 2300 ml of resin per tank at $50/3.5 liters
|Fiberglass makes these tanks durable and clean. Cost was about $60 per 40"x47" tank.|
|I'm filling this tank with water to test for leaks|
|The deeper tanks on top will be wicking beds. The shallow 12" tanks underneath will be bioponic grow beds.|
I'm not concerned about toxins from the fiberglass resin. If you are then use LG-730 Mono Epoxy Pool Paint or Pond Shield. for the finish coat It will add $10-$20 per tank
These same tanks would cost only $20.00 each if pond liner were used.
Box - 5/2 = 2.50
Liner - 100/9 = 11.00
Bottom - 12/2 = 6.00
After one year of use I found that the bulkheads needed to be tightened. I expect the wood expands and contracts with changes in humidity which eventually caused them to loosen.