Quick lighting question about VHO's


New member
I'm setting up a couple all VHO fixtures. My ballasts are going to be external from the fixture, only bulbs and reflector(obviously endcaps and wires) will be in the box. The question is, being so low heat production from VHO bulbs, do I need to add fans to the lighting box?

One setup is a 3X95W 36" and the other is a 4X110W 48".



New member
They do get pretty hot not like MH, I use 4 computer fans blowing in, my canopy has 6 bulbs 48" my IceCaps are mounted outside. I guess you could just try and see how much heat puts in your tank, or if it's open you might not have a problem at all, plus the cooler the lights last longer.


New member
If any part of the hood is open, they should not get too hot. Functional life quality and quantity of a bulb is extended by keeping it cooler.


In Memoriam
i've got 4 x 110 over my 55 with a hood and it gets my tank hot...seen it up to 83.9 one day...I've got a sump in the fan! also my canopy has the whole back open so it's not even fully closed. ballast is also mounted on the outside of the canopy.


New member
VHO's definitely are hotter than T5's - but IMHO they are worth it.

SITC carries a 6" Air King fan 200cfm at about 37db - I can't say enough good things about these silly fans.

Currently I have a 4x54w T5 fixture and a Velocity T3 pump on our 150.
The temps were hitting as high as 84.5^.
I put one fan over the sump, and one in the canopy - it now runs a constant 78.5.


New member
Do a temp test of the same wattage of vho and T5. The T5 will be much hotter. John at FAOIS temp tested them.