DIY Canopy pics...any suggestions?

[jackdp]

Attached are some pics of my DIY hood in progress. Its just about to be stained and finished, then I plan on adding a fan and the MH retrokit I bought along with my 2 old 55 watt PC's Anybody see anything I forgot or something I could add to it. Thx!

 

[reefrunner69]

Anybody see anything I forgot or something I could add to it. Thx!

Yep....you forgot to install the MH and send it to me

 

[jackdp]

I knew it! I hung the thing over the tank and have been sitting here wondering why the tank isn't any brighter...I forgot to put the light in it (does that help) You keep trying kevin, maybe eventually I'll slip up and send this MH to ya

 

[reefrunner69]

Looks great! Is it gonna be a pendant? Or does it sit on the tank?

 

[jackdp]

The plan right now is for a pendant. The canopy I have now with PC lights sits on top of my 20 long and causes heat issues. I'm hoping the pendant will help keep the heat down with the addition of the MH.

 

[Electrobes]

man very nice canopy.. I am so happy for you!

 

[fishfreek]

Is it gonna be a pendant? Or does it sit on the tank?

I know its a pendant but if you look you will notice the lack of ability to get to the tank with out taking it off the tank it if was going to sit on the tank. Man if it was going to sit on the tank that would be a real PITA to have to take the entire thing off the tank every time you needed to get into the tank.

 

[BillyZ]

Looks very nice! Make sure you fan blows out, not in.

 

[fishfreek]

Make sure you fan blows out, not in.

I always prefered to have the fan blow in vs out. Cool air in vs Hot air out.

 

[BillyZ]

I don't have any practicle personal experience so take that into consideration. But the majority of advice I see in the DIY section says that cooling is more efficient if the fan draws air out.

With this particular canopy I think it would be even more applicable as the vent holes are directly over where the MH will go, therefore draw cooler outside air directly past the bulb to cool.


JMO

guess it's time for me to google some thermodynamics info )

 

[fishfreek]

Well my thinking is that hot air rises and with vent slats directly above the bulbs the hot air will want to go up thru those slats. having a fan pulling air out will basicly have to pull the air back down thru the slats counteracting the natural desire for the air to rise out.

if you pushed cool air into the unit then the warm air would rise out of the top thru a higher internal pressure and thru natural warm air rising effect.

 

[BillyZ]

good points.

This is a pendant though... hmmm

well I just downloaded a textbook on heat transfer and thermodynamics... i'll see if I can glean anything out of that.

 

[BillyZ]

sorry, I'll share the link )

http://web.mit.edu/lienhard/www/download-ahtt.shtml

 

[BillyZ]

k... I now know more about thermodynamics than I ever wanted to know... and I still don't know very much lol. I'm also reminded of why I changed majors in college from engineering to CS.

anywho... things to consider in this debate:
This is a pendant, is the bottom of the pendant enclosed? therefore making this a sealed unit to direct airflow? (if not, you may wish to consider it, it will help with keeping the tank cool)

The vents are located top and center of the hood, however, there will likely be a reflector of some sort located above the lights and, therefore, between the light bulbs and the vents themselves.

can you give us a little more info on the placement of the bulbs and reflectors in your hood JackDP and if the you plan on putting a glass/plastic bottom on the pendant?

 

[jackdp]

There will be a single spider reflector mounted in the top of the hood. It will be mounted via 4 screws and kept approximately 1/2 inch away from the top to allow for airflow above the reflector. The reflector itself has vents in the top of it to allow heat to escape above the reflector and thus through the top vents in the hood. I've cut holes for 4.5" fans on each end of the canopy but only plan on putting in 1 fan initially. I already have the second fan if I find it is needed. There will be a 21" 55 watt PC bulb mounted in front of and in back of the MH (centrally mounted.) Ballasts will be located remotely to keep ballast heat out of the hood. At this time there are no plans to cover the bottom of the hood, this can easily be added in the future if it proves to be a problem.

And fishfreek..you are correct, if it did sit directly on top of the tank it would be hard to get to the water :lol

 

[TheMadNucleus]

Hi Jackdp,

I've built a few of these and thought I'd just mention a few things I thought about when building some of mine.

First off - looks really cool - nice job.

It seems that the reflector is already mounted on the inside (I am not sure about this but I seem to see it through the cut out for the fan). Just wanted to suggest - and you may have already thought this out - that you should be sure to finish the inside of the canopy with whatever finishing material you are using (a good suggestion is polyurethene). I suggest this cuz I made the mistake of not doing this on one of mine - i.e. only finished the outside, and sure enough, the dampness from the tank (dispite covers etc.) managed to effect the wood.

Bottom line on this: Since it is wood used over a water based container - best to have it totally sealed.

Another suggestion - something I discovered very useful on one of my canopies - I mounted the timer directly in the canopy along with override switches which alow you to turn the canopy on even if the timer has it off. I placed switches on a strip of aluminum, routed an opening in the front of the canopy and recessed this into the front. Looks very cool and provides full control of all lamps from the front of the canopy.

Anyway - the monster looks great. Hope to see pictures when it's complete.

Tom

 

[fishfreek]

How high will this hang above the tank? There is a big loss of light the higher it goes since more light will end up around the tank than in it.

 

[jackdp]

Just wanted to suggest - and you may have already thought this out - that you should be sure to finish the inside of the canopy with whatever finishing material you are using (a good suggestion is polyurethene).

The inside is painted with a gloss white enamel to aid in reflection of light. The outside will be stained with a polyeurathane stain.

How high will this hang above the tank?

What do you suggest? I was thinking of hanging it only as high as I have to to make getting to the water for testing and feeding easy. I will probably also use open hooks and chain to hang then I can raise and lower by pulling up links as necessary. i.e. I can raise it 10 links higher and lower every week or so by a few links to aid in acclimation.

 

[fishfreek]

So it would be like 6-8" above the tank?

I wouldnt mind kevins advice here but I would think a thin sheet of clear plexiglass between the bulb and the water could be of help. It would zero out the chance of the water getting onto the hot bulb and causing it to blow plus it would make the canopy an air chamber for the fan and vents to operate.

 

[reefrunner69]

My CSL pendant came with a glass splash shield, one of the first things I did was remove it, my MH bulb is about 7-8" off the surface of the water with nothing between it and the water. Aarons is better and safer advice, but I haven't had a problem.