Plexi glass top on tank & T5 tubes & heat
 

I'm in the process of planning a small terrarium/grow tank. The current idea is to use an 90cm/36" ExoTerra tank with a plexi glass top plate. And 4x 24W T5 tubes for lighting.

How much heat will the lights generate? Will I (or the plexi glass top) get into trouble/melt if I place the fixture directly on top of the plexi glass top? Would it be better to mount the fixture in a hole in the top plate?

I had 5 T5 on the two terrariums (now replaced by LED) (each one had 5 :)). My husband put lamp on small wood sticks (plexi glass, on it 4 sticks, on them thin MDF with lamps). It's still alive :) The height of sticks is about 2 inches, distance between glass and lamps - 1/2 inches.

My plexi lid warped within a year or two of installation. It absorbed the moisture from the tank and expanded on the bottom side. Go with glass instead of plexi.

Glass top might be a good idea. Plexi glass is easier to manipulate. My idea was to drill some holes in the top in order to get wiring into the tank, and some ventilation. Seems like I will have to rethink some aspects...

So drill holes in the glass.......

Easy to do if its not tempered. Lots of companies will do it for cheap if you don't have a diamond bit.

I've got the same (?) 18x36 tank and I'm using a 1/4" acrylic (plexiglass) top.

It bends a little bit (as you'd expect) but isn't an issue.

My lights heat it by about about 3'f. I'm using a "300 watt" LED.

Raising it 4" off the top of the lid didn't matter for temperature, but I didn't bother to measure difference in light levels- I expect it'd be a minor difference.