# How many watts would this be?



## ARLINGTON (Oct 8, 2007)

I'm new to planted tanks and have been struggling with the lighting situation for my 5ft tank, 100gal. Currently I have an inefficient diy hood with 10*40w, 48inch,T12, Phillips daylight deluxe bulbs. The lights that i have seem ok, but, I'd like the light to be more intense. I have been looking for something that i could do for about $150. Would it be safe to assume that 2 of these (see link)would make 400w or would it only be 80W?

http://www.pclightingsystems.com/fl/40bulbbuy.html

Thank you!


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## trag (Jan 9, 2008)

Two of those would be 80 watts of fluorescent lighting. As you might expect, the same wattage of lighting provides differing amounts of light, depending on what technology is used to convert the watts into light.

But most of the wattage recommendations you'll see are referencing an electricity to light conversion which is in the ballpark of fluorescent lighting.

Okay, now that that's all out of the way, go to http://www.1000bulbs.com/2-to-200-Watt-Compact-Fluorescent-Screw-In-Light-Bulbs/ and browse their amazing selection of screw-in fluorescents. They have 105 watt screw-in fluorescents, which, by the marketing on the page you referenced, would be the same as a 420 watt incandescent bulb.

And now that that's taken care of... how wide is your tank? I have a 6' X 2' X 2.5'H aquarium with a similar lighting system to what you tried. We built it with ten 40 watt T12 lamps about 20 years ago. A big problem is that T12s are 1.5" wide. So ten of them shoulder to shoulder is 18" wide. That's too close together. Half the light is going up away from the aquarium, and it can't get back through all the crowded together light bulbs, even if it does have a reflector to bounce off of.

Two T12 bulbs need a reflector about 7" wide. So, at most, one can reasonably fit six T12s (or maybe 7) over a 24" wide tank.

This is why you are much better off using T8 bulbs or (better still) T5 HO bulbs. They are 1" and 5/8" wide respectively and a pair of each of them needs reflectors 5" and 3" wide respectively. You can see where you can fit a bunch more of them over the tank, and have most of the misdirected light recovered by the reflector.

Furthermore, T8s or T5s with a good electronic ballast are about 20% more efficient than standard T12 bulbs with a magnetic ballast.

A 4' long T5 HO bulb uses 54 watts. Eight of those with good reflectors would probably deliver 2.5 times as much light as you were getting out of your ten T12 40 watt light bulbs.

The problem is that I don't think that you can get eight T5 HO lights withinyour budget. If you build it yourself, you can get ballasts which drive four T5 HO bulbs for $50 each here: http://www.ballastwise.com/item.asp?PID=24&FID=15&level=1 Sockets are available back at 1000bulbs.com for about $3.50 each (T5s use a smaller socket than T8s and T12s). Eight bulbs need 16 sockets, which is $56 and that's your budget right there. 2 X $50 + $56 = $156 and that doesn't even include shipping costs. Then you would still need light bulbs ($6 - $8 each if you shop around and don't need the fanciest thing) and reflectors. Reflectors are really the hard part. One can make one's own pretty affordably. If you start with a 5" X 48" piece of reflective (mirrored) metal it can be bent into this shape http://www.io.com/~trag/Aquarium/T-8DualReflector.jpg scaled down by 5/8 for T5 vs. T8, yielding a 3" wide reflector which will service two T5 bulbs. Or you can start with any cheap sheet metal (roof flashing, e.g.) and then coat the shaped metal with reflective mylar.

The problem is that bending metal into that shape is very challenging for most people, unless they happen to have a 4 foot wide sheet metal brake laying around.

Alternatively, buying reflectors is easy, but tends to be expensive, in the $30 - $50 per reflector per pair bulbs range.

Hmmm, or you might get T8 bulbs. This ballast at $15 each http://www.ballastwise.com/item.asp?PID=31&FID=13&level=1 will drive four T8 32 watt bulbs. And you could use the same sockets from your T12 rig. But eight of them with really good reflectors would only deliver about 30% more light than your ten crowded T12s. And eight of them at 5" per pair would cover 20" of aquarium width. Still, the two ballasts would only set you back $30, leaving you with $120 for bulbs and reflectors.


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## ARLINGTON (Oct 8, 2007)

thank you! lots to think about!


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