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post #1 of 4 (permalink) Old 05-14-2011, 03:11 AM Thread Starter
Algae Grower
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New To Forum and CO2

I have a 100gal Acrylic aquarium with 4 T5HO lamps at 54 watts each for a total of 216 watts. Is this still considered medium light?

Thank you
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post #2 of 4 (permalink) Old 05-14-2011, 03:30 AM
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I assume the tank is around 24 inches high. If so, 4 T5HO bulbs will give you very, very high light, far more than you will be able to manage well. Of course, if you have that light hanging at least a foot above the top of the tank, the light won't be nearly as bad.

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post #3 of 4 (permalink) Old 05-15-2011, 01:06 AM Thread Starter
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Now you have confused me, thats less than 3 watts per gallon. And this is very high light? Just trying to figure this part out. The tank does have a CO2 system on it.

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post #4 of 4 (permalink) Old 05-15-2011, 02:16 AM
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Watts per gallon doesn't take height into consideration. If, for example, you have a 54w bulb directly on top of a 55g aquarium, that's 1wpg. And yet if you were to suspend it ten feet above the aquarium, that's still 1wpg. Similarly, at substrate level, a bulb above a 12" high tank vs. a 24" high tank will have massively different lighting levels, regardless of no change in wattage.

In addition to height, a 48" T5HO bulb gives off drastically more light than a 48" T8 bulb.

In addition to height and bulb type, a good (versus nonexistent) reflector on the bulb can increase lighting by 2-3 times. So a 48" 54w bulb with a good reflector might produce twice as much light as the same exact bulb with a poor reflector.

Anyway, forget about watts per gallon. It's useless for our purposes. Check the PAR sticky in the lighting forum here for more information. Oh, and listen to Hoppy. He tends to know what he's talking about
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