250w MH's 4.5" from water. Water / heat dilema

[taku]

I just mounted a pair of 250w MHs in my hood. Unfortunately we built the hood only about 8" tall and now the lowest part of the MH bulbs sit about 4.5" from the water. No way around it at this point. Should I be concerned about water splashing onto the bulbs?
I'm pretty concerned but wanted your opinions before constructing some sort of barrier.
Also, I have not yet turned the MH's on to see how much heat they put out but I'm curious... we installed 2 6" fans in the back towards the center, blowing into the hood. They put out a tremendous breeze and my PC's are never warm to the touch when on. Should I be concerned with the heat output of the MHs or do you think my setup will be sufficient?
Thank you!

 

[jester]

I take it you don't have a glass canopy. Yes, you should be concerned. AS you know they get very hot. Tank water is cold (relitave to lights). Cold water on hot glass is not good and asking for trouble. Also, have 1 fan blow in and 1 on the opposite side of the hood blowing out. This will help prevent your lights from heating your tank. If both are blowing in, it's like a hair dryer. If both are blowing out, you will have a lot of salt creep all over the lights and everything elese. Make sense? Cool.

 

[taku]

It's a custom wood canopy But your concern is all I needed to hear as far as the lights needing protection from the water. Does home depot carry any sort of plexi-shield I can custom fit?
About the fans, great info! I'm somewhat confused however. The canopy is 5 feet long. Both fans sit dead center, sideby side blowing in. They are actually 6" desktop fans I bought at home depot. They are adjustable with 2 different speeds and I can tilt them and angel them wherever I want in the canopy.
They have the remaining area, about 2 feet on both sides, to blow hot air out. The whole backside of the canopy is open.
Do you still suggest one blowing in and one out? If so, I have a lot of work ahead of me, but it can be done!
Thanks again!
edit: maybe I'll add 4, 4" exhaust style fans on the sides of the canopy?

 

[dburr]

I don't think plexiglass would stand the heat.
You built the hood so can't you build another "frame" to mount the hood on? It would only need to be about 4" tall. Or just hang it from the ceiling if you can.

 

[taku]

Actually guys.. i think you're on to something. I'm going to modify my hood. It's going to suck, but there's just no other way around it at this point. I'd rather spend $20 now in modifications than $60+ for new mh bulbs later.
Thanks very much!

 

[nasotang00]

60+ bucks on new bulbs but that doesn't include all the small glass fragments that will be in your tank, fish, corals etc. That 60+ could turn into humdreds!!! Be carefull.

 

[jester]

What I ment by a glass canopy is what you are refering to as a plexi shield. Plate glass over the tank below the lights (6"). The extra fans on the sides is a real good idea. If you keep the back open, then have all the fans suck air out of the tank. this way, airflow will come from the back, over the lights and out the tank. to test this, get a cigar(if your of age) and watch the somke airflow. this will help you asses your progress.

 

[taku]

Jester & everyone: I really appreciate your input!
After all your suggestions I now know I should just put in the time to do it right and increase the distance between bulb and water by modifying the canopy.
I'm curious, however, has anyone ever seen a canopy with some type of door in the front for easy tank access?
I ask because the top of my canopy is currently 6.3ft off the floor and although I'm 5'9... I still have a hard time doing ANY work on the tank unless I'm on a chair.
Thanks again!
Mariam

 

[jester]

<a href="http://www.reefmaniac.com/" target="_blank">http://www.reefmaniac.com/</a>
check this out. I'm going to build something similar. (doors in front of canopy).