Join Date: Jan 2004
Location: Vancouver, Canada
I prefer uncovered lights, but until now (well, soon) I've yet to be able to implement it. Water evaporation and the resulting electrical corrosion has been an issue (yep, fluoro user here).
The new Hagen tanks (yech, they're awful, but anyways..) use that type of idea:
The canopy is one piece and slips over the edges of the tank (no more tank rim, just a glass lip) and the light fixture actually hangs right over the water unshielded. To protect the electrical they have screw-on caps with a rubber gasket/grommet that makes it practically waterproof (severely water resistant anyways). End result is really great lighting.
My main beef with covering the tank first is all the light wasted. You lose some spectrum simply through the glass (the thicker the glass, the worse it gets), so plants will already suffer, plus you lose intensity over time simply from all the gunk and deposits that build up on the glass surface to filter light out.
If you can shield the electrical from the moisture I'm all for uncovered lamps as long as fish can't jump up into the fixture and get stuck.
Working with glass is actually extremely easy, though you need some equipment. I typically use 3mm clear window glass - it's cheap and easy to work and thick enough that it doesn't break too easily. You need a good, strong ruler that won't slip around on the glass (I ran some duct tape on one side of it for extra friction). Then you hold it in place and score the glass with a glass cutter (hardware stores sell them - it's like a miniature rolling pizza cutter). Flip it and put some pressure on the middle of the glass while tapping a hard object (like the back of the glass cutter) on the back of the score you just made.. Eventually you'll weaken the glass enough that it'll give and you'll have a clean cut.
Problem is now you have a really sharp chunk of glass. I have a diamond drill bit (impregnated with diamond flakes or somesuch) that needs to be water-bathed to keep cool.. I doubt it's standard fare nor cheap. But that's what I use to grind the glass edges to make them touchable.
OR, you could just take precise measurements and call up a glass shop and ask them to cut and smooth the edges of a new piece of glass with the dimensions you give them. There's a minimum charge but it's really not that much - I pay something like $10CDN around here to get small things cut.
77 gal fresh: South Americans + plants w/ 4xT5 NO
65 gal reef: Nothin' w/ 4xT5 NO
33 gal brackish: Gobies w/ 1xT12 NO