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Re: light bulbs and tannins

> I don't understand this reasoning. When people suggest a certain # of 
>  watts/gallon they're making the recommendation based on brightness, not 
>  power consumption. So if these bulbs really do put out the same brightness 
>  as a 75-Watt bulb, why would you only consider them a 20-Watt bulb for 
>  overall lighting calculations?
Rules of thumb such as a certain # of watts/gallon are not based on 
brightness.  They are based on power consumption of a FLOURESCENT light tube 
(and not incandescent).  Of course it's not a precision scientific method, 
but only intended to be a rough, ball-park suggestion as to how much light 
you could reasonably expect to need over your average tank (whatever that 
is).  The screw-in CF bulbs such as the Lights of America bulbs are not 
marketed as intended for use over aquariums.  Instead, many aquarists have 
just experimented with them and found that they can be a cheap solution to 
putting a lot of fairly good quality of light over a tank.  For example, I 
run three 45 watt Lights of America tubes inside the hood over a 29g planted 
tank, and that gives me a nominal 135 watts of pretty good quality 
flourescent light to the tank, or approximately 4.5 watts per gallon.  I have 
no idea if it's precisely 4.5 watts per gallon.  It could be less; it could 
be considerably less; I don't know for sure.  I would guess (the key word 
there is 'guess') that the quality of light is probably close to a Warm White 
tube.  But my plants do well under this light, and the tank looks pretty 
bright to my jaundiced eye, so that's about all I care.  For the 
Do-It-Yourself'er, the CF lights are a fairly cheap solution to the problem 
of how to put lots of light on the plants without spending your kid's college 
education fund in the process.