well I just got a new house, with a garage for the first time and on the side of the garage is a cut out in the wall, my guess is its for a freezer and trash can. but the area is 72" by 36". So I was thinking of building a frame out of 4x4s? or 2x4"s and then putting another 2x4 every 10-16" laterally. then a 1/2" piece of ply to layer the inside and just drop in a pond liner...... i have about 2kGPH for pumps. so how tall can I safely go with the tank? how high can I safely go with my framing design. here is a small picture of my idea. the black is plywood inside the frame which is the brown parts. just to give even support for the pond liner.