light / heat build up

[aaron]

I am making a light unit for my new 36g bowfront and i'm concerned about transmitting heat from the lights (1 x 175w MH and PC's) to the tank water.
I am basing the design on a pendant style so i dont trap the heat in a big hood over the tank. My question to everyone is: i notice a lot of MH pendants have glass covers over the front and i was wondering if this would help to control the amount of radiant heat coming from the bulb, forcing more heat to exit via the exhaust fan or doesnt it make any difference?
It seems like the glass would help to block some of the heat by keeping it inside the pendant rather than radiating it staright into the water.
opinions anyone?

 

[bad coffee]

Yes, it would. It also keeps water from splashing on hot bulbs.

But it also filters out some of the light. DE bulbs emit lots of UV, so they are all covered with UV blocking glass. Since you're going SE, it's up to you.

B

 

[aaron]

Do you think the trade off of less light to avoid boiling the tank is worth it?

 

[House of Laughter]

Aaron,

Do what you need to do to manage the health of your animals - and work around that. I have a 250w DE pendant that is about 18" over the water of my frag tank. It heats up the water and doesn't have a hood on it, it just hangs out there.

House

 

[alrha]

fans should be able to wisk the heat away.

 

[aaron]

I understand what your driving at house but i am attempting to make the best possible lighting solution for my new tank and i'm asking advice as to the best way to achieve this. ie is the trade off between light intensity and heat dissipation worth considering this design option

 

[bad coffee]

how far above the water surface will the light be? also, will it be a true pendant, or ar you going to set it on the tank?

B

 

[aaron]

I was thinking about making legs for it to sit about 6-8 inches over the tank,
I saw a interesting design of legs online, where they are hinged so you can flip it out of the way when you need to get into the tank

 

[aaron]

As far as heat goes, i am using two fans: one at each end and i have cut slots in the top of the unit to let the heat rise out. still not sure if i should put glass over the front to block heat or not.

 

[yessongs]

FWIW, i have a 250W & PC over a 25, doesn't raise the heat much. Its a Pendent about 12" from bulb to water with glass. 6-8" over tank with no glass is not good if water splashes on the bulb it would break. JMO

 

[aaron]

Thanks for that yessongs, i think i'll be going with the glass cover over the bulbs.
I'll post a couple of pictures of the unit in the diy section soon