Equipment Question

I measured the top part of my aquarium. From one end of the rim to the other it is 48.5". It is a 75 gallon.

I am trying to figure out what size lighting fixture to order but they only come in 48". The bulb is 47-1/8" long not counting the prongs. The light fixture on the tank now is 48-11/16ths from lip to lip. It has lips that hang over the edges of the top of the tank. It is more snug than the pic shows. I left more play in the picture so the lip is more visible.

My question is, is the 48" measurement of the fixture a generic term or is it exact? If that is the case then there is a risk of the assembly falling in the water because it will just be sitting on the edge of the aquarium.

In case the question got lost in the babble I will recap. Pictures may help clarify.

Edge to edge of the top of the tank - 48.5"
Fixture that came with the tank (no brand name) - 48-11/16" - includes lips to secure to tank (see pic)
Bulb in fixture is a Coral Life E40 T12 and measures 47-1/8"
 aqtop1.jpg   79.33KB   0 downloads
 aqtop2.jpg   76.6KB   0 downloads
 48and11sixteenths.jpg   66.56KB   0 downloads

My 48" fixture, a Solar T5 from Catalina Aquariums, fits fine on a standard (All-Glass Aquariums brand) 55 or 75 gallon tank. I'm pretty sure the tank sizes are quite standard across manufacturers. I've been very happy with that fixture, and I was also impressed with their customer service (a part damaged in shipping was replaced 2nd-day air at no cost to me).

I think the 48" designation just means the fixture is built to fit a standard 48" bulb.

Edited by gzeiger, 14 September 2009 - 01:19 AM.

All fixtures that I've seen have been a little larger than 48" inches. As already said it would seem that they are made to fit the standard 4ft aquariums which usually measure 48.5" or slightly larger. Many of the fixtures also have mounting legs which elevate them slightly and those are typically adjustable giving you a much larger range of tolerance.

You could also get some hinged glass tops for peace of mind. These also cut down on evaporative water loss. As I recall the tops for my 75 set me back about $35.

You could also get some hinged glass tops for peace of mind. These also cut down on evaporative water loss. As I recall the tops for my 75 set me back about $35.

Glass tops also cut down greatly on fish suicides.