wattage lighting for BIG tanks
 

These people use it with CO2 to make enormous
plants, but still recommend more than 1W per gallon without CO2. I'm
wondering does this wattage change the larger the tank gets?

Yes. It's only a rule of thumb, and breaks down with very large or very small
tanks. In the case of very small tanks (say, 5 gallons or less), you may need
8 watts per gallon or more. With very large tanks (over 100 gallons), 2 watts
per gallon may be too much, even with CO2.

This page sheds some light on this: ;-)

http://www.thekrib.com/Plants/Tech/Lighting/

The graph uses a logarithmic scale, so you have to read it carefully, but it
indicates that even Amano (known for his high-tech, high-light, CO2-injected
tanks) sticks to 1 watt per gallon or less for tanks 100 gallons or more.

The reasons for this is because, once you're past 75 gallons or so, tanks
generally don't get deeper as they larger; they just get longer and wider. And
depth matters the most. Also, bulbs are more efficient if they are longer, so
watt for watt, you get more light from the longer bulbs you can put over a
longer tank.


Leigh

http://www.fortunecity.com/lavender/halloween/881/

wattage lighting for BIG tanks
 

These people use it with CO2 to make enormous
plants, but still recommend more than 1W per gallon without CO2. I'm
wondering does this wattage change the larger the tank gets?

Yes. It's only a rule of thumb, and breaks down with very large or very small
tanks. In the case of very small tanks (say, 5 gallons or less), you may need
8 watts per gallon or more. With very large tanks (over 100 gallons), 2 watts
per gallon may be too much, even with CO2.

This page sheds some light on this: ;-)

http://www.thekrib.com/Plants/Tech/Lighting/

The graph uses a logarithmic scale, so you have to read it carefully, but it
indicates that even Amano (known for his high-tech, high-light, CO2-injected
tanks) sticks to 1 watt per gallon or less for tanks 100 gallons or more.

The reasons for this is because, once you're past 75 gallons or so, tanks
generally don't get deeper as they larger; they just get longer and wider. And
depth matters the most. Also, bulbs are more efficient if they are longer, so
watt for watt, you get more light from the longer bulbs you can put over a
longer tank.


Leigh

http://www.fortunecity.com/lavender/halloween/881/