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Lighting a tank with a small top...

RamPuppy

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Moderator
Swords...

I have a 30 gallon Hex that has always been difficult to light, and truth be told, I have always thought to effectively light it I might have to get a metal halide pendant and hand it a few feet above the tank... but that is not only expensive, but energy wise, cost prohibitive to me (my airconditioner more than the energy for the light!
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Any how... I had an idea that struck me, but I am just not sure about it's feasability.

I was thinking of using 3 24" tubes and mounting them vertically on the back 3 panes of glass, outside the tank. Then, encasing them in wood with a reflective surface inside, and THEN, mounting mirrors inside, that would reflect up into a mirror on the top of the tank... (So you wouldn't look in at the lights...

hmmm... reading this, it all sounds pretty ridiculous...

and the thought has just struck me to turn the tank on it's side.. and just mounth the lights on one pane...

oh heck.. I don't know... it'd be a shame to waste the nice stand!
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Oh man, I've wanted a large hex tank (200+ gallons) for a long time I love the shape but metal halides would be a requirement on one that size.
What is the width of the top of your hex? If it's 24" you can buy a prebuilt twin tube compact flourescent reef light sized 24" x 12" with your first two bulbs all for like $99-$150. Check marinedepot.com for either a premade power compact lighting unit or parts to build your own lighting canopy.
I like to use parts locally available at hardware shops so if I were setting it up I would just get a couple 42 or 65 watt Flourex compact flourescents (6500K screw in compact flourescents by Lights of America) or DAYLIGHT spectrum screw in compact flourescent bulbs. Perhaps 3 bulbs arranged as a triangle in a custom wooden hood or even just two bulbs side by side in the center of the hood should be fine for a hex tank only 24-30" high-especially if you line the sides with tinfoil/mylar). These bulbs will be fine if you are sure to buy "daylight" spectrum or 6500K (check the packaging closely) as they will have a far more even color balance as well as more intensity/lumens since the bulbs are clearer.
 
Hi,

just as a note, it is not true that metal halide lamps do need more energy than fluorescent lights. The efficiency is normally even better with metal halide lamps, so you do get the same light levels with less heat. The difference is the size of the lamps. MH lamps are quite small so they do get much hotter than big fluorescent lights (with the same amount of energy).

I'm using a 4200k 70W MH-lamp as additional light source in winter for my nepenthes. Those lamps are often used as "shop-lights" here in Germany, so they are quite cheap available through Ebay.

One thing to consider with MH lamps is the light source is very small. With just one lamp very sharp shaded areas below the plants are the result. Fluorescent lights do produce a very diffused light in contrast.

Joachim
 
thanks guys...

I think the top is 20 inches or so across, but I don't have it right now, so I'll have to check.

Joachim, I know halide is cheaper to run energy wise, that is not what I am worried about... those little bulbs put off a lot of heat, and my air conditioner in my 12000 sq ft apartment, is the same size they put in the complexes 700 sq ft apartments... cheap idiots... it can not handle the load it should... so by adding more heat sources, I am dooming myself.
 
Hi Ram !

If you install, lets say 10000 lumens of flourescent or 10000 lumes of a good metal halide light, than the metal halide will NOT(!!!&#33
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produce more heat !!

Look how much energy the lights consume and all (99,x %) of this energy will turn into heat (light will convert into heat, too, when it hits the plants, soil, etc...)

If your metal halide lights with 6500 lumen consumes 80W (70+10) and you need two 40 W flourescnet ligths to get about 6000 lumen than both of them will heat your room with 80W !!!
No matter which of both is hotter.

Martin

You can burn your finger in a candle (hot but small) but you can't heat a room with a candle !
 
MArtin! Thank you!

I by no means can afford a metal halide right now, but you have made me happy knowing that I will be installing one soon, maybe around christmas time!
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Martin, your confidence in metal halides is making me more interested in trying my ex reef tank MHs on my "large" highland tank (4 ft L x 4 ft H x 2ft D). I've been avoiding using them because of worries over heat and needing to mount them far above the tank.
I currently have 175 watts of compact flourescent and 80 watts of normal output flourescent. This heats the tank to 80-85*F in summer.but since autumn has arrived the temp is only 73-75*F depending upon room temp. If I can get more light from a 250W MH with roughly the same heat I would be pretty happy (not that I'm unhappy now of course). I did read that you can't use plexiglass under halides-which is what my DIY tank is topped with...
Any thoughts?
 
hhhmmm...It is correct that the 10000 lum from each will be converted to heat from both bulb types but the MH will produce more heat at the lamp itself. I believe per lum the florescent produces less overall heat due to efficiency as it produces more lum/watt than most others. The MH bulbs are great for producing a whole lot of lum in a small space though and are much more efficient than standard filament bulbs but still produce less lum/watt that compact forescents.


joe
 
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