New Aluminum Light Hood

[EdMiller]

I've been having issues with the heat in my current light hood causing my bulbs to fail way too soon. I'm running 2 x 250w MHs and 2 x 96w PC actinics. It is the actinics that are not lasting as they should. I have two fans running on the hood, one blowing in, the other pulling out, vented to the outside of the aquarium canopy cabinet. The hood is just a simple box I made of 1/2 plywood to hold the light kits that I got from J&L when I set up my reef tank. There is a 1/8 acrylic lens to protect the bulbs from water splashes

I decided that I needed to get rid of more heat, so I am building a new hood from aluminum. It will use the same two fans in the same configuration, but it will employ some passive cooling methods as well which I hope will reduce the internal temperatures of the hood. Basically, air will be able to circulate up from the lower edges of the hood and out throuugh vent holes in the top. Also, being aluminum, it should dissipate more heat then the wood.

I started with some 1/2" aluminum U channel. I cut V notches in the channels to form them into frames for the hood. There are three frames, one at each end and one in the center.

To these, I then riveted on the backing pieces which will support the light sockets and the polished aluminum PFO reflector. There are aluminum channels riveted along the bottom that will accept the acrylic lens.

I made the end panels and cut out the holes for the fans (I will drill the mounting holes when I install them) then riveted them onto the end frames.

Next the skin is riveted onto the outside of the frames. The top skin has vent holes drilled in it to allow heat to escape. The frames create a space between the reflector and the outer skin for the air to move through.

The electrical box on the top will accommodate all the cords and wire connections for the lights and fans.

Now the hood itself is built, and a coat of paint is applied.

I will be switching to VHOs from the PC, so the next step is to get the sockets, install and wire them. Then I will strip out the old hood and move the MHs and fans into the new one. Total investment so far, $50, or about the price of one PC bulb. I hope it works.

 

[danskim]

Looks pretty good. Nice work, Ed.

 

[EdMiller]

I finished it up today and installed it.

here is the buisiness side all assembled.

All the wiring connections are made in the junction box on top. I made all the light cords the same length now, and the fans are spliced into one cord instead of two.

Here it is installed in the cabinet.

This is the old hood that this one replaced.

 

[xrunner1234]

Looks good. Nice and lightweight.

So what's the difference in temperature rise between the 2? What was the internal temp before and after? Just curious. My gut tells me that it will only be a few degrees at best, but I may be wrong.

 

[WZHANG]

Thats pretty fancy stuff. I'm impressed. How hard was cutting the pieces for the skin? And what did you use?

 

[Bommi]

Nice work. Did you cut the aluminum on a table saw? If so what blade did you use? Also, do you know if you can use a router on aluminum? Thanks.

 

[Mufasafish]

I've cut up to 1/2" aluminum on a table saw with a carbide tipped blade. A router works well for trimming the outside edge of aluminum but not so well if you drill a small hole and try to enlarge it. It will chatter and grab making a rough edge.

 

[EdMiller]

I don't know what the temps are like yet, but if nothing else, it looks way better One of the things that gave me this idea was the recent article in Advanced Aquarist's that showed the drop in temperature in a pendant fixture with just a small vent hole made in the splash shield.

I bought most of the sheet aluminum pre-cut to the sizes I needed, so there was very little cutting to do. The outer skin is just roof flashing (I had it on hand all ready), but I think I'd go a bit thicker if I were to do it again. It comes in a roll 9" wide. To cut it the simplest method is to use a straight edge and score it with a utility knife. Then you just bend it on the score until it breaks.

I have a simple homemade sheetmetal break that I used to bend the pieces to fit. I used a router and a circle cutting jig to make the holes in the ends for the fans.

 

[trueblackpercula]

Nice work

 

[rrasco]

Blast from the past...

Good to see though, good idear notching the tubing for bends.

 

[plapczynski]

Really nice.

 

[EdMiller]

The hood worked well since building it, but is now up for sale as I've upgraded to a Vertex LED. I looked at several of the LED builds that some have done, but chose to go premade when the local shop had the Vertex on at a great sale price.