If you are not comfortable with doing electrical work a professional could assemble this for you and it would still cost less than buying a commercially made setup.
The body of the lightbox needed to be light and strong and have some resistance to warpage and moisture as it would be suspended over the tank and would be subjected to some incidental splashing just by the water movement instigated by the powerheads and the return pump. The box for the electronics needed to protect the electronic ballast, provide cooling in the summer months, and also house the switches for the lightbox.
With the above in mind, I decided to construct the lightbox and the electronics box from wood as this would be the easiest medium for me to get the most out of for the least amount of funding. The lightbox was to be made from Whitewood (a very clear white pine) and the electronics box from MDF (medium density fiberboard). The display tank is 48" long so it was pretty obvious that 48" VHO bulbs would be the way to go.
The trickiest part I figured would be getting the power from the ballast to the lightbox.
This problem was easily solved with harnesses that I picked up from a local electronics shop. The harnesses were actually two, nine wire, two foot long harnesses that I cut in half, spliced in three additional feet of wire, and enclosed the wiring in a standard spiral wire sleeve.
I would only need eight of the wires in each harness but this was the only harness I could find that would do the job. I could have used four trailer harnesses, one for each set of four wires. The trailer harnesses had an upside in that they are relativley waterproof but they were more expensive.
If you do some research and have the money you can get harnesses that are used for underwater lighting and cameras that will do a great job. I did not have the resources for these types of hookups. The harnesses I used cost about five dollars.
A decision will need to be made here as to whether the lightbox will be constructed using nails, screws, or the dowel pin/biscuit method. The latter is recommended but if you do not have the resources you can use screws or nails to construct the lightbox. If using screws or nails, I highly recommend galvanized drywall/deck screws or nails.
For those of you that are familiar with biscuits and dowelpinning I will not list the needed tools or materials here because it is subjective to your own experience, I used both methods because I had them available.
These lists of materials can be altered to construct any size light fixture or ballast box you want. It all depends on the size, type, and number of bulbs you want to use and the size of the ballast(s). Be creative with your own design, this design fit my particular needs. Eventually, down the line, I will probably want to add some Metal Halides, but the VHOs were definitely the best starting point for me.
Tools Needed for Both Units
Here is a list of tools needed for this project:
Materials for the Lightbox
Materials needed for a lightbox that will house 4-48 inch long VHO bulbs:
Materials for Electronics Box
This list of materials is personalized to the project I am working on and should be tailored to fit the needs of each situation differently. The unit I made was to be attached to the wall behind and above the display tank, it very easily could be altered to fit inside the cabinet underneath, or in an area behind the wall out of sight. My choice was based solely on the fact that I have installed the main power for the whole project up on the wall behind the tank area so as to avoid any situation where water could compromise my outlets, but that is a different project.
Optional materials might include some L.E.D. lights and other bells and whistles you might want to add. I put lights on both the ballast circuits so you could see that they were on and a lighted fan switch, these are just fluff and perform no function other than I could do it and they look cool!!
If you wanted to you could build timers into the box to turn your lights on and off, I just plugged them into the cheap on/off timers but I might get a little more advanced on some later project. I have seen some very cool setups with whole circuit breaker panels built into the cabinet underneath with everything wired into them and hidden away. Trick it out if you can!!