diy lightbox / hood

[justDIY]

although I'm not going to have time to build this for a few weeks, I'd like to brainstorm the idea a bit in advance

I want to build a "lightbox / hood" to hang over my 30 gal, which is being converted from goldfish storage into a planted community

my plan is to make a 5" high rectangle that is approx 50" x 20" out of birch plywood

in the middle of the box (about 1/2 way through, I'll affix a sized piece of plywood to serve as a 'shelf' or divider, one side will hold the lights and reflectors, the other side can hold the ballast and food/supplies

the part the holds the light and reflectors will be enclosed on the bottom with a piece of glass to protect the bulbs from splashes, and to aid in cooling. I plan on using aluminum flashing painted high-gloss white as the reflector ... white instead of polished so as to avoid re-strike caused by a flat reflector

on one of the short sides of the box will have two cut-outs for 60mm muffin fans to exhaust air from the light box, and the other side will have vent holes drilled to allow air in, as well as switches for lights / fans / whatever.

I plan to hang the box from the ceiling via two eye hooks put into studs and some nice looking brass chain, with eye hooks also at each of the boxes four corners

inside the light portion of the box, I plan of having my two newly acquired 96 watt pc's in the middle and two over-driven t8's (fo32t8) (only doing a 2x overdrive) toward the outside, with the pc's sharing a ballast and the t8's sharing a ballast ...

why t8's you might ask? well, I have at least 8 ge spx50's stored away when I bought them online a while back, so I figured I would use 'em up (burn em up?) ... plus hanging the hood two or 2.5' above the tank will end up wasting some of the light, so having overkill amounts makes up for this

so how's it sound ... crazy? cool? too much work?

hehe, feedback appericated, negative or positive

thanks
Gordon

 

[fishfreek]

I think your gonna be REALLY impressed at the output of those dual 96W PC's. The florecent lights are really un needed but as you say your intent is to use them up.

With the entire rig 2 1/2" above the tank are you going to rig up a pully system so you can rase this up out of the way when you need to service the tank? If not then what did you plan on dowing for say water changes or when you had to get your hands wet so to speak?

I think the glass is un needed aswell. If you got water splashing up on those bulbs then I would be somewhat supprised since the bulbs are going to end up being an inch or so inside the canopy so they would be like 3" or more above the water surface. THe glass will also end up difusing your light somewhat.

Those are just my ideas.

 

[justDIY]

um ... sorry, I think there's been a mis-understanding ... the unit is going to be about 2 to 2.5 ft above the tank ... that way I can look down into it like a 'pond' or see through underwater like an aquarium

(hence the overkill of 192 watts PC and 128 watts T8HO) ... I might only run the pc's for about 8 hours, leaving the t8's on for 12 ... or the other way around, leave the pc's on for 12 hours and bring the t8's on for 8 ... that first option would help the pc's last longer

good point about the glass and the likely hood of water splashes being minimal ...

does it make sense thinking of the glass as another 'wall' in the box?? ... I had planned on mainly using the glass to help create a 'sealed' box so that airflow could be created over the bulbs in a more controlled fashion (similar to what placing a hood ontop a glass canopy accomplishes)

upon further thought on that matter, it might still be a problem, since end of the bulb nearest the air intake will receive 'cold' air from 'outsid'e, but the other end of the bulb would receive hot air heated by the bulbs, unless I made the fans move the air fast enough that it didn't have time to heat up much ... but then that would create a whole lot of noise!

I wonder if it's really nessecary ... I would like to keep these bulbs a little on the cooler side (under 150°F?), to get a bit longer life out of them, but at the same time, not cause cold spots by cooling one part of the bulb more than other parts

heh, at my old job before going solo, we had a mechanical engineering department with many people that loved thermodynamics ... they coulda told be the best way to acheive even cooling with minmal noise

may just routing some slots into the aluminum reflector and putting a single fan above the reflector directed out the top of the hood would provide enought 'up-draft' cooling to slightly cool the bulbs, without the need for a large (and heavy) piece of glass

my plan on moving the hood out of the way for major surgery and such would be a pair of double ended clips, I'd just clip one link on each chain to a higher link, shortening the chain and getting the contraption out of the way ... sounds resonable enough?

keep the feedback comin, please

Gordon

 

[fishfreek]

Oh my. ya at 2' above the tank your gonna experence aLOT of light displacment.

I have to wonder if your gonna notice the difference with the t8's on or off as from another post I see you have now seen how bright those PC's really are.

At that height above the tank I would say you wont experence any direct heating from the lights into your tank. The heating will more or less be indirect by increasing the air temperature around the tank.