The total cost of this project was $39. It provides 160 watts of 6500K Normal Output fluorescent light. The lights are 48" long.
Pedro (milalic) and I found these shoplight fixtures that cost about $9 each at Home Depot:
Each fixture holds two 40 watt Normal Output fluorescent tubes - available at Home Depot too. This is the label on the boxes:
The bulbs that Pedro found are 6500K and are well known for their low price - I believe he paid about $5 for two of them:
The fixture that holds the bulbs is open ended. There is no side wall or shield. We added a DIY side shield (end cap) made of a tin shingle that costs 39 cents (2 of these were enough to make 4 end caps):
Using household scissors we cut the shingle in a shape that matches the profile of the light fixture. The incisions on the sides are made so you can bend the material and provide 2 "wings" that allow the end cap to be fastened to the light fixture with small nuts and bolts:
The nuts and bolts used to fasten the end cap in place are very small size:
Additional support for the end cap is provided by slipping the thin metal under the plastic supports of the bulb sockets:
The end cap from inside. The nuts and bolts that hold the end cap in place are to the left and right of the bulbs (somewhat hard to see on this picture):
The light fixture is is placed over the tank using small diameter threaded metal rods. The rods are screwed into the tank plastic rim. There is one nut that provides additional support at the base of the rod:
Close up of the rods:
The rod comes in different lengths, this one is 36" and it was long enough to make 8 short rods, about 4" each:
Specifications for the rod:
The nuts used to support the base of the rod:
Front view of the 75 gal. tank:
The work to make this powerful light was very much minimal. The only downside that I personally saw was that the bulbs are not entirely enclosed - you can see about 1/4 of the bulb from the front. I don't like even a little light glaring in my eyes but from what I've seen Pedro is not the only person that doesn't mind that at all.
Another thing is that the inexpensive 6500K bulbs seem to come only in lengths of 48 or more inches.
An alternative to the 48" 160 watt light that we made could be a 216 watt combination of four T5 54 watt 10K bulbs ($50 shipped) with a Workhorse 7 ballast ($45 shipped) which totals about $95 for the 4 bulbs and ballast only. All other hardware has to be either bought or handmade.