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Discussion Starter · #1 ·
First off, I'm not sure if I should post this here or in the DIY section, but since it's largely lighting related I feel like I'm more likely to get better answers here.

I'm thinking of building a hood for my 55g aquarium and would like to use it to distribute light in my tank more evenly/return light that is reflected off the waters surface. Currently I have 3 possible ideas on how I'm going to accomplish this. Either through corrugated steel(shed roofing) painted with white paint or using firebarrier(the OSB with a reflective coating) and the final idea is making a glass enclosure and putting a mirrored tint on it. My question is which of these would give me the most even distribution of light, or would there be a better way to accomplish my goals?
 

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Discussion Starter · #5 ·
At least here in Corvallis, Or. there is a store that sells individual reflectors for lights. If you can locate something like that then you can put individual reflectors behind each bulb and that will yield the absolute best reflection.
Each bulb has a reflector already. I'm building a new hood and figured as long as I was I could add some reflective surface the width of the tank for a more even distribution rather than having a bright spot directly under the ballast. Sorry if my OP wasn't clear enough.
 

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Discussion Starter · #7 ·
No real need to put a reflective surface in the hood if the reflector goes half way around the bulb. There is very little light reflected by the water in relationship to what the bulbs put out.

What type of bulbs do you have and how many do you have?
2xT5HO 54W with icecap reflectors, suspended 4" above the surface. I figured the reflective surface would be a minimal yield but I have all the materials(other than the glass) for any of my ideas so why not increase the efficiency even by a tiny fraction? My main concern is that I don't want to create hotspots.
 

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I wouldn't use two T5HO bulbs to light a 55 gallon tank, especially not with very good reflectors. That is far more light than you need or can easily manage. Improving the efficiency won't help at all. Better would be decreasing the efficiency by putting a layer of fiberglass window screen over the light to reduce the intensity. Or, raise the light to about 10 inches above the top of the tank, but that will result in a lot of spilled light.
 

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2 bulbs might be ok if you have control over each individually. I'd still find a good sealant for the canopy and the two part epoxy does a good job of protecting the wood from the moisture. I've used it for years for that along with protecting the inside of a stand on a sump based system.
 

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Discussion Starter · #10 ·
I wouldn't use two T5HO bulbs to light a 55 gallon tank, especially not with very good reflectors. That is far more light than you need or can easily manage. Improving the efficiency won't help at all. Better would be decreasing the efficiency by putting a layer of fiberglass window screen over the light to reduce the intensity. Or, raise the light to about 10 inches above the top of the tank, but that will result in a lot of spilled light.
Hm. You have me a bit confused, I based my lighting choice on your sticky and calculated at the substrates thickest point I should have 80-100 uE/m2/s. I see how this would be an error, as it shoots up quickly. What would the signs of too much light be? Algae growth, chlorosis of top leaves?

I'm trying to increase the spread of the light because my glosso is looking leggy, and i want to use the interior of the hood as a diffuse reflector for an LED moonlight. Would I be better served decreasing the light efficiency and putting in a spotlight over the glosso? Or might the legginess be from something other than light?
 

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CO2 is much more likely to be the problem with poor ground cover growth. And, getting the CO2 adjusted right is probably the most difficult part of keeping a "high light" tank.

Many of us are coming to believe that "too much" light just means more light than is needed to achieve the growth you want. With good CO2 you can get good growth of almost all plants, including ground covers, with only 40 micromols of PAR at the substrate. That makes having more light than that "too much light". When you have too much light avoiding algae is a full time job, pruning is a twice a week job, and any small mistake you make can cause the tank to quickly become a mess. Fast growing plants will grow so fast they hog the CO2 and most of the other nutrients, causing the slower growers to become unhealthy and easy prey for algae. Like most things involved with planted tanks light needs are subjective and still evolving.
 

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Discussion Starter · #13 ·
Hoppy:
Thanks for the info, I'll definitely start reducing the lighting. Should I gradually step it down, removing one reflector, waiting a week, removing the other reflector, waiting a week, then adding the fiberglass screen? Or drop it all at once?

Makes my hood build a lot easier now since its no longer going to include weird angles for the reflectors, and I'll place whatever reflectors I end up putting in it for the moonlighting above the light. After a bit of research it does seem CO2 is the problem with the glosso, again it seems I may have too much.

Superwen:
Love that reflector design. Depending on a few things I may copy it and put a less reflective coating for my moonlighting.

fresh.salty:
Does the 2-part epoxy paint come in clear? Since any reflectors I put in the hood are now going to be solely for moonlighting I'm thinking the irregular brightness of the metal in the shed roofing would make a good diffusion surface so I want to coat it in a clear protectant.
 
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