Difference in W/G for PC, Fluorescent, and Halide

[Small Fry]

I know that for most tanks, depending on what you want to grow, that a good rule of thumb is 3 - 5 Watts per gallon. Is this 3 - 5 W / gal of standard fluorescent, HO, VHO, PC, or metal Halide.

I read that a PC is approx 3-5 times brighter then a NO fluorescent of equivalent wattage so 3-5 watts / gallon of PC should be much brighter then 3-5 watts / gallon of NO. Does this mean that I could replace my NO with PC of same wattage and end up with more light???

Does anyone have alternate scales for wattage for different types of lighting??

I want to increase the lighting for my 20G marine but don't want to increase the wattage too much to reduce temperature problems and be reasonable with my power usage for my tanks.

 

[daza]

I think replacing a normal fluorescent with a power compact of the same rating will give you the same/very similar lighting, but the power compact will be physically smaller.

Here is a pretty indepth article that might answer the rest of your question.

 

[rdd1952]

There aren't any regular flourescent lights that I'm aware of that can give you 3 plus wpg unless you completely cover the top of your tank with them. Flourescents don't have very high wattages. To get over 2 wpg, you almost have to go up to PCs.