Negative WAF: need "low" MH canopy

[steensuder]

I recently purchased some second hand MH lamps.
They are the shoplight type and when my wife saw them she simply rejected to accept them anywhere near the 530L planted aquarium in the livingroom :-(

My idea to use two of them (150W each) and making a canopy they could reside in, means at least 30-40cm added on top of the tank. This she rejected on the spot too :-(

I'd still like to make a canopy that sits on top of the tank (a requirement, must shield the light entirely) and I have access to stainless steel sheets and machinery that can "work it".

The default reflector gives light in a 92x94 deg. "pyramid" but I think it'll be better to construct a new reflector in alu. I've seen a so called Spider Reflector mentioned; is that a concept to go for?

My best idea at the moment is a full cover canopy made from stainless steel sheet, that add no more than approx. 15cm on top of the tank giving me approx. 18cm from water to top of canopy.

The tank has a clearing (inside the upper alu-frame) of 50 x 155cm.
Now, I'd just like to have a > ~90% light coverage at a 10-15cm depth.
From my rough sketches I can see that this should be possible.

Next idea is to utilize fans in the canopy. I've just read that this is necessary, but how serious a problem is it?

Another issue is where to insert the glass needed to separate the MH-bulbs from the humid environment above the water.
As I see it there are three options:

1. Old fashion sheets of glass sheets resting on the tank frame.
2. Glass sheets fixed in the canopy somewhat "close" to the water.
3. Tempered glass just below the bulbs and reflectors.

The whole idea with this post is to ask for thoughts, do's and don'ts and new ideas, so... please ;-)

Most examples found on the Internet are canopies made with no regard to elegance and design so I'm a bit blank here.

NB
Unit conversions: 1L = 0.26 gall., 1cm = 0.4inch.

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Best regards,
Steen Suder

[GulfCoastAquarian]

If you're goot with forming sheetmetal, then I'd go ahead and make a reflector that doubles as a housing. It could come out very attractive-looking, but keep in mind it will also get very hot.

If it were me, I would still build a canopy, but instead of it being 30-40cm (~12-16") tall, make it only 10cm (~4") tall and hang it 10-20cm above the tank. You could cut a groove in the canopy to slide a piece of tempered glass to shield the bulbs and help filter out some harmful UV rays.

[steensuder]

Originally Posted by GulfCoastAquarian

If you're goot with forming sheetmetal, then I'd go ahead and make a reflector that doubles as a housing. It could come out very attractive-looking, but keep in mind it will also get very hot.

I've thought of this myself, but I'm new to DIY MH, so I'm not quite sure exactly how hot 150W HQIs will get.

Originally Posted by GulfCoastAquarian

If it were me, I would still build a canopy, but instead of it being 30-40cm (~12-16") tall, make it only 10cm (~4") tall and hang it 10-20cm above the tank. You could cut a groove in the canopy to slide a piece of tempered glass to shield the bulbs and help filter out some harmful UV rays.

Due to WAF hanging light above the tank is no option. I have to agree with her: the MH light is not very pleasant anywhere but in the tank. At least not in our livingroom, which is very cozy with a lot of diffuse lighting from lamps with paper lamp shades.

At the moment I've placed some books on the tank to imitate the shape of my sketch. This proposal gives approx 20cm (8 inch.) from water to top of canopy. This, again, gives me approx. 15-16cm (6-6½ inch.) from water to bulb. I'll wait and see what she says to this... arrangement ;-)

Perhaps, I could build a reflector that follows the shape of the housing with an inner distance of 1cm (½ inch.).

Having a distance between the housing and the reflector would take a bite out of the heat, wouldn't it?
I still want to ventilate the compartment where the bulbs are.

I've also access to 0.5mm (1/50 inch.) alu-foil that could be used for reflector.
How do I polish this to be mirror-like?

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Best regards,
Steen Suder