Re: Aquatic Plants Digest V2 #287

> From: "A. Inniss" <andrewi at u_washington.edu>
>   [Original Poster]
> > > using the four 48" fluorescents I had hanging above the tank, I'
> > > about using all compact fluoresents inside the hood. I want to h
> > > penetration of light to the bottom of the tank and the nice effe
> > > comes with high intenity lighting. My aquarium is 20" deep. I do
> > > go as far as MH lighting, I think that is over kill. I was plani
> > > PowerCompact 6700K Ultra-Daylight bulbs, how many ?
> > 
> > What is the wattage?
> > 
> > > So, is this a good idea or not ?
> > 
[Erik (me) replies]
> > You won't get any more light into the tank than you would with the 
> > same wattage of NO florescents.  The only advantage is that you 
> > can pack more in.
> 	I'm not sure what is meant by this statement: CFs give out more
> lumens per watt than NO flourescents, according to the charts I've seen,
> so I would think that you _will_ get more light into the tank.

You took my quote out of context.  The original poster was confusing
compact fluorescents (9W and 13W U-shaped tubes) with Power Compacts (48"
tubes).  The former are basically THE SAME efficiency as normal output
fluorescents (maybe less, as the usual classic magnetic tar ballast you
must use with them gets significantly hotter than with the equivalent 18W
& 24W "normal"  fluorescents). The latter, on the other hand, are supposed
to be as efficient as you can

His idea was to use Power Compacts, but cites as evidence that they
"penetrate" better his 9W compact fluorescent being able to grow a small
patch of algae in the area of light concentrated right under the tube.
If you fill a 100-gallon tank with 9W CF's, you'll use up the same (or
more) energy to get the same light output as if you use 48" Chroma-50's on
a shoplight.  

Based on some of the stuff I found, Power Compacts are somewhat better
than NO's, but still not as good as T-8's.  We're looking at 65-75 lumens
/ watt for NO T12's, 80-85 lumens/watt for Power Compacts, and 89 lumens /
watt for instant-start T8's.  13W compact fluorescents check in at 69
lumens/ watt.  (Original data grabbed from

  - Erik

Erik D. Olson					         amazingly, at home
eriko at wrq_com