dmh
Member
Okay, I did a little research to try to clear up my (and others) confusion regarding this whole 'watts per gallon' debate. Obviously saying the 'watts per gallon' rating is the same for VHOs, PCs, and MHs cannot be true do to efficiency discrepencies. Also, the 'gallon' is really meaningless, the depth is what's important. If you have a coral under 4 feet of water, it will require a much brighter (at the source) light than one at 12 inches, but we all know that. A tall, thin tank will require higher intensity lighting than a large shallow tank, even if they are the same volume.
Anyway, I was able to determine a 'lumens per watt' rating for each type of lighting system, and thereby able to include efficiency in determining the sufficiant amount of light.
Let's assume that the 4-6 watt/gal standard that was always used for VHOs is correct, and let's say 5 watts is what we are after and we have a 55 gal tank, so we need 275 watts of VHO lighting. This 275 watts, (this all assumes 8-10K daylight, you get far less lumens from actinic) will yield 14850 lumens. (*note, this is far more than the 10K lumens/square meter that has been cited other places, but we will assume the 14850 is correct.)
In order to achieve the same lighting with power compacts, you need only 175 total watts, and with metal halides you need only 165 watts.
NO flourescent produces 65 lumens/watt
VHO flourescent produces 54 lumens/watt (some energy is dissipated as heat)
PC produce 85 lumens/watt
MH produce 90 lumens/watt
There is some variance between brands, but generally these rating seems to hold true.
Does anyone know how much light is TOO much for corals? Anyone ever 'wilted' one?
Anyway, I was able to determine a 'lumens per watt' rating for each type of lighting system, and thereby able to include efficiency in determining the sufficiant amount of light.
Let's assume that the 4-6 watt/gal standard that was always used for VHOs is correct, and let's say 5 watts is what we are after and we have a 55 gal tank, so we need 275 watts of VHO lighting. This 275 watts, (this all assumes 8-10K daylight, you get far less lumens from actinic) will yield 14850 lumens. (*note, this is far more than the 10K lumens/square meter that has been cited other places, but we will assume the 14850 is correct.)
In order to achieve the same lighting with power compacts, you need only 175 total watts, and with metal halides you need only 165 watts.
NO flourescent produces 65 lumens/watt
VHO flourescent produces 54 lumens/watt (some energy is dissipated as heat)
PC produce 85 lumens/watt
MH produce 90 lumens/watt
There is some variance between brands, but generally these rating seems to hold true.
Does anyone know how much light is TOO much for corals? Anyone ever 'wilted' one?