Deb and I started our fish collecting business here on Moloka'i in 1989 with a whole slew of 55g glass tanks which we built ourselves. Wanting to keep the tanks out of the elements, we decided to put them in the single carport attached to the house that measured 10 feet by 20 feet. We could have built single stands for each tank, but there wasn't much space and we needed to cram as much gallonage into it as possible. We also needed something that was inexpensive to build, and it didn't need to be "pretty". Since we were somewhat nomadic at the time it had to be easy to put together, take apart, and transport.
After spending some time researching the prices for what materials were readily available on Moloka'i, we came up with a design. Cinder blocks and 4 x 4's were about twice the price that we were used to paying on the Mainland, but they were heavy duty enough to get the job done quite nicely.
The racks start with 1 1/2" x 8" x 16" cement base blocks on the floor (our 55g tanks are 16" deep). These are spaced out the length of the bottom tanks. Two wood 4 x 4's are then placed on these. We put the edges of the 4 x 4's even with the edges of the base blocks. This left a 7" gap between the 4 x 4's. Next we stacked three 8" x 8" x 16" cinder blocks on the 4 x 4's over each of the base blocks. On top of the blocks went another pair of 4 x 4's placed to the edges of the blocks.