Suggestions for new T5 light placement?

I don't believe there are any ill effects to placing that light directly on the glass hood in terms of heat buildup, and I have read that the glass hoods remove very little light intensity. I am running a similar lighting setup (24" T5 sittng on a glass top over 30" tank) with no problems so far. Since the light is shorter than the tank, legs may help light get to the sides of the tank more easily.

I have a planted freshwater tank and no real SW experience, so I can't comment about burning corals.

Carlsonr said:

I don't believe there are any ill effects to placing that light directly on the glass hood in terms of heat buildup, and I have read that the glass hoods remove very little light intensity. I am running a similar lighting setup (24" T5 sittng on a glass top over 30" tank) with no problems so far. Since the light is shorter than the tank, legs may help light get to the sides of the tank more easily.

I have a planted freshwater tank and no real SW experience, so I can't comment about burning corals.

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You are on the right track fresh water guru =). It is better to keep the light off the glass... the legs idea is better ....

You can build your own canopy with wood just avoid the soft woods like pine... birch or oak would be good choices.

You can retro fit the hood and I suggest visiting the hydroponic plant stores. They carry a material called Mylar. Reflective stuff and glue it down and or staple it to the inside of the wood to reflect more light down.. have an open back and a tiny computer fan or something to keep air flow going.

The glass is a good thing to have to prevent splash up (some fish do it) and water on hot bulb = shatter. Plus it will keep the evaporation down.

-Nemo- said:

no problem. ty Carlsonr.

it turns out i should have ordered the 24" fixture when i ordered these :swear:

i DO NOT want to return them if i do not have to. the shipping fees, waiting, the calling etc. ugh!

all i want to grow are "beginner" soft corals like on these pages.
http://www.chehaliscoral.com/page.php?id=12

http://www.aquacon.com/Begcorals.html

the 24" is the same except an extra 4 watts on each bulb (total of 48w instead of my 40w)

can anyone suggest if i should sit this right on the glass to make up for it being 18" and 8 wats shy of the 24" or is this light fixture just too small to grow the corals i listed for this tank?

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Soft corals are good starter ... the lights should be sufficient. Depth +watts matter most... watts per gallon is a guideline only and it is not accurate.

IF you do build a simple hood and use mylar, it will look nice, the lights wont light up your entire room =p, and it will cut back loss of light cause of lack of reflection without.

IM and idiiot you did provide the link...nevermind..be back in a bit after i have time to read a bit ..plus i have work to get done.

IM back: dear god I am not on my A game today..sorry for being such a DOLT.

That fixture would be ok ontop of the glass yes...but like I said earlier suspending it by wire or using legs...

There are kits also that put a swing arm like thing to the tank so you can lift it out of the way... I have to dig later.. or you can.

Should be in lighting accessories at marine depot site.

its fine on the glass ...i will make that totally clear =)...I just have a thing about being electrocuted ...i dont like it. =) so for safety I suggest the legs or mounting brackets for fixtures.

The only issue with having it directly against the glass is providing adequate cooling for the bulbs themselves. Good cooling can increase intensity by as much as 20%.

Also, to add to Amphiprions statement, it will also make the bulbs last longer if you keep them cool by suspending the light a little off the glass vs resting directly on the glass.

As far as intensity of light, I know in the other thread where I was talking about it I didn't mention percentages. On my PAR meter, when measuring with and without a glass top, it was only around a 5% decrease in PAR output with the glass on. Yes, it does reduce the light a little, but 5% is nothing when you figure in a MH bulb loses something like 20% of its intensity the first 90 days on its own.

On the topic of a canopy, that fixture can be used in a canopy, as long as you provide active cooling like the computer fan suggestion mentioned above. If one were to decide to go a canopy route I would still suspend the fixture at least an inch below the top of the canopy so your not resting the fixture against the top. The ballast/metal on the fixtures get pretty warm and I would almost guarantee you will blow the ballast fairly quickly if one were to mount a fixture like that directly to the top piece of wood on a canopy. No were for the heat to go if you do that. Just suggestions, take them for what they are.