Cecil, while you have a little time to burn, try sticking a bead of sealer on the black 180 gallon tank and see if it sticks. I'm concerned that you will have a hard time finding a sealer for it.
Actually I won't have to worry about it. It already has a drain installed, and I'm using Uniseals to slide the axle ends through the biofilter tank. (AES 2010 catalog pg. 364.) The part of the axle that goes through the tank walls does not rotate, and the frame will secure to both ends on the outside of the tank to keep them immobile. I may have to build the frame a little longer but that's not a big deal.
