10-09-2007, 07:39 AM
Join Date: Apr 2005
Location: Brentwood, CA, USA
iTrader Positive Rating: 100%
| | Re: 2-4 watts/gal of what kind of light?
Watts per gallon has never been more than a very rough estimate of how much lighting to get for a given tank size. And, that is all it will ever be. It is very easy to debunk it as a "rule". Take a 15 inch deep tank, add 2 watts per gallon. Now make the tank a third deeper. Light is just barely attenuated in 5 inches of water, but the watts per gallon rule would say you need a third more light for the same intensity. We could shift to a PAR based rule, but how would a light manufacturer be able to assign a PAR value to their lights? PAR would depend on too many variables. Then, we would still use watts per gallon for our first crude guess at how much light we need.