Their are many ways to build a stand. This design has served me well over many fish houses. I use planed 2x2" which is packed at 44 - 46mm. Screws go all the way through. This flimsy looking design has taken 24" wide tanks with a rack capacity of 2 and a half tons. I think this was as far as the design was safe to go in a 3 bay arrangement.

First stand up & varnished. Note the open top layer. This gives an extra tank over 3 bays.

Viewed towards the door. Note the gap between the stand & door. This will be a packing area & somewhere to put the microscope.

Note the daylight coming through. The fish house was designed for maximum light exposure.
The photo to the right shows the basic design of the 'A' frames.
This design has proved to be very strong.
These bays are 48 & a half" (the half inch is useful to allow for errors such as twisting of the frame etc.) to facilitate either 6 15x8x8" or 2 -24x12x12" or 1- 48x12x12".
It is important to put 2 screws through each side of the horizontal bearers. This prevents the stand from twisting. The opposite bearer can be fixed with a single screw.
Those requiring more work can rebate the butt joints.

Centre stand towers constructed. These are 18" wide & required a stronger stand made from planed 3 x 2".

Fresh water stand completed. This will feed the bottom 3 layers of tanks by gravity. Eventually these tanks will be replaced with drilled base tanks & 75% of the fish house will be water changed by the flick of a tap.

Fresh water stand at far end. Two large 70 gallon tanks to be put on bottom row.

At this stage the fish house resembles a cross between a building site & somewhere to keep fish. Note brine shrimp hatchers on the floor & temporary striplights set up over the tanks

Centre stand during wiring up

Centre stand during wiring up

Wired up & ready to go. Note stand supporting roof centre. Whilst a foot of snow is unlikely I had in mind walking on the roof to clean it up & replace plastic fixtures which do perish.

Note striplight position. Tanks will be drilled for drainage. Pipes will pass through the centre of the stand.

Fry tub stand tagged onto the centre stand.

Fry tubs. These are wallpaper roll soaking tubs from B&Q. The plastic is safe for fry & they hold one gallon.
Note home made filters made from the bottoms of lemonade bottles, a few stones, a short piece of old hose pipe & some filter material purchased off the market for £2 for a dustbin liner full.
Cheap & effective.

Fry stand shown tagged onto centre stand.

Stand from other side showing dehumidifier which takes out about half a gallon per day.