lighting help

[iwantareef16]

Okay i have my lighting down on my 55 and put it on my 20 planted tank and everything took off. It is a 20gal high tank 24 in wide with a 2-4 foot lights on it. So can anyone figure out my wpg?

 

[tetrin]

i'd say roughly 40W in 20g ~ 2 wpg

 

[greenmaji]

Roughly 10watts per 12" of bulb thats actually over the tank minus a little for restrike depending on how efficient the reflector is.. so just a little bit less then 40 watts.. about medium light.. your likely getting a little light from the light coming in from the sides of the glass as well.. this would be impossible to calculate in my opinion..
EI (enviromental intellegents) would be the only way of actually getting a good idea how much light you have, in other words comparing how well the plants grow compared to more traditionally lit tanks..

 

[malkore]

yep, should be half of each bulb over the tank, so 2x40w/2=40w/20=2wpg medium light