Canopy Question

I'm building my canopy and cannot figure out if I should leave the back open or not. I realize heat may be an issues with the metal halides but I'm also concerned the light spilling out onto the wall behind the tank may not look too appealing.
Any opinions on this?

 

Installing a fan is a good idea.

 

install a fan, and leave a area for intake for fresh air. also read about convections, you can move air without fans

 

I would leave it open and get a custom screen kit and build a screen to cover the back to still allow air to flow in but prevent fish from jumping out. Then put exhaust fans pointing out the top of the canopy. That's how my canopy was designed and I'm liking it so far. Nothing worse than losing fish to jumping.

 

Here is a pic of the rear of mine. I have three fans, two blowing out and one blowing in. I also have the two square vents to allow air to circulate in and out. The only thing I wish I would have done differently was to put the fans on the sides blowing across the water and sucking out the other side but they would be more visible then.

I do not have MH's but have no heat issues. I also have four 3"x3"+/- holes in the top for heating fans from the light units to blow out of.

 

Here are some pics of mine. It is fully enclosed on all sides and top. There are 2x250w MH and 2x140w VHOs for lighting. I have a single 120mm (4") Vantec stealth DC fan mounted in each end, both blowing in, and powered by a variable voltage DC power supply (wallwart type for $5 at Harbor Freight or WalMart) so I can vary the fan speed according to the heat load during different seasons of the year. I found having equal size 4" holes in the top or ceiling of the canopy works better than open back for heat removal. With the fans blowing cooler dry air in the moist hot air rises out the top. Even when the fans are not running you can feel heat rising by convection alone.

The front has two hinged doors for feeding then the whole front opens for cleaning and maintenance via a full length piano hinge. There is also a second piano hinge further back so the whole top opens for complete access to everything. Note how I installed the reflectors on a sub panel so there is air circulation above the reflectors, this allows heat to rise above the panel and out the top without light escaping and hitting the back wall or ceiling.


The fans in conjunction with a clip on fan over the sump work so well I sold my 1/4HP chiller a couple months ago, it had not run April 2008! I might also point out I am in Phoenix AZ where it gets very hot and we have a digital setback thermostat on the house AC so it is warm all day long until we get home and the tank stays 79-81 year round with fans only.