I would like to say that it took a lot of trial and error to figure out how to build these racks,but that is not the case. My first centralized system was set up for my mother's pet shop nearly 15 years ago, and most of them that I have built since have followed the same design. The only variations have been for breeding tanks where I had to worry about fry being sucked into the overflows. I'll cover a couple methods to prevent that toward the end of this article, but as my nickname, pleco breeder, indicates, I don't usually have to worry about small fry unless I'm simply breeding a species to see if I can do it.
The first step to setting up one of these racks is to get all the materials together. The main reason for this is to get the dimensions of the tanks, or totes as the case may be. I use clear Rubbermaid storage totes, rather than aquariums. This has several advantages, as well as a couple disadvantages, but I still prefer them.
The biggest advantage has to be the ease of drilling. If you use aquariums for a central system, you have 3 options for drain lines: drill them, order pre-drilled tanks, or use some very creative plumbing to siphon water over the top of the aquarium. Unless your local fish shop has the ability to drill tanks for you, very few do, you're going to pay quite a price and have a 6-8 week wait while the tanks are shipped in as a special order from the manufacturer. It is not uncommon to see a $20 per hole price tag just for drilling. As for the siphon method, it can be quite slow, and will not allow for the current preferred by rheophillic fishes. I'll go into more detail about the siphon in a later article. It makes for a really nice automatic water changer when set up properly.
The plastic totes on the other hand, can easily be drilled with a common hole saw and drill. The trick is to support the inside wall by resting it on a board while drilling. I would advise painting the outside bottom of the totes before drilling them. In my experience, light reflecting from below the fish tends to stress them, and could be the difference between a spawn and some really healthy fish. Besides, if you are going to paint the bottoms, you don't want the hole being there to allow any chance of paint getting on the inside of the totes.
The first step, beyond getting the totes, is to get enough lumber to build the shelving to hold them. I normally set the totes 3-4 wide on each of 3 shelves. This prevents
the weight becoming excessive on any single shelf and still allows for plenty of tank space. The frame itself is made from 2*4's and wood screws. Each shelf is covered with
1/2 inch plywood to give support to the center of the totes. Because most all totes have what is apparently intended to be feet on the bottom, I then lay 1/2 inch carpet padding
on top of the plywood. This gives enough support to the area around the feet to prevent them from cracking and draining all over the floor.
