WOW!!! This tread and build have really come out of know where an is Just amazing all round.
I would like to know the dimensions of the tank and how and with what you sealed the tank.
What thickness of ply? I also noticed you used pieces of wooden angle in between the seams of the floor and walls to form fillet joints.
I have thought about using this technique, did you use nails or screws to attach the wooden fillets?