T5/MH combo question

ksfulk · Apr 24, 2015

I wasn't getting any response in my build thread, so I thought I would post here for some more visibility.

I'm having some second thoughts on my lighting choices. I was speaking with a local reefer and he is wanting to part with a 60" 250w MH/ t5 (4x54w) fixture for a very reasonable price. However, I have an issue, as the tank is 60", so the light would be rather tight once its in the canopy (1.5" clearance on each end). Would that be enough clearance to support the air movement around the end of the fixture? I like this fixture as it has 3 - 250 MH, rather than 2 that come on most standard 48" fixtures. I plan on using aluminum exhaust fans for ventilation in the canopy, but I dont have any experience with MH to know if thats going to be enough. The basement typically stays around 66-68F in the summer and winter, so I dont think there is too much of an issue in the way of heat transfer to the water, but I dont want to pose a risk to the fixture, my tank or my home either. Thoughts?

GrampaDon · Apr 25, 2015

No way that will be enough clearance around that fixture.
Mabey you can cut some 5in hole in the canopy at both ends.?
Or remove the glass from under the fixture. And add more fans blowing at the MH to help. So you know the 2nd method will likely increase you'r evaporation rate in the tank.
Lastly you might do away with the canopy. To get better clearance around the light.

ksfulk · Apr 25, 2015

Cut 5" holes where and for what reason? Im confused by this statement.

The glass for the fixture is necessary because its a DE MH and i don5 want to nuke my tank with the UV or end up with an exploded bulb(s) in my tank. The canopy is to be set with 4 - 4" exhaust fans to provide circulation and heat exchange, so there will be air movement.

The whole point of the canopy is to keep the light in the tank and not in the room - its a requirement by the boss, and i refuse to argue with her. Happy wife, happy life.

With 4 exhaust fans in the canopy, and 4 or 5 cooling fans (i cant recall exactly how many) at the top of the fixture and 1 fan at each end - im just not sure if the circulation at th3 ends is critical or not. Can I compensate for the lack of space on the ends with more air velocity?