Re: Lighting effiency

> From: gomberg at quake_net (Dave Gomberg)
> fluorescent T8, GE rare earth, electronic ballast (!), 2650 lumens, 27 watts,
>   98 lumens/watt  (part is T8 and part is electronic ballast)
> MH, E37 VBU, 31000 lumens, 400 watts,
>   78 lumens/watt
> With the figures above, why would anyone go MH?  They are expensive,
> dangerous, and black body at best.  

Easy.  Six GE whizbang bulbs (I'm assuming 48" long) would give me
6*27*98 lumens or 15876 total lumens.  If I managed to ideally get all
that focused onto the top of my 2'x4' tank (0.74 m^2), I would have
11,800 lux.  Two 175w MH give me 2*175*78 = 27,300 lumens or 20,300
lux.  11,800 lux at the surface is marginal for high light plants in a
2' deep tank.  And if I want the bulbs suspended over the tank so the
top is open ...  Basically, I need all the light I can get over my
tank and I'm willing to pay a premium for it. 

Anyway, how much are these "hot" GE bulbs and ballasts?  Would enough
of them to equal the output of a pair of MHs be that much less?  I
think the reef people decided a long time ago that MHs are more cost
effective over the long run (energy usuage and replacement costs)
than VHO bulbs in a high light environment.  

> Why not go for phosphors tuned to
> plant needs?  I am not saying such a tube exists, but I am saying it
> is the best choice.  Sylvania MUST have data on GroLux, it's been out
> for 40 years.

Well, so far we don't really know what the plants need.  And, I have a
two-fold purpose for the lights - I want the plants to grow so they
make the tank look nice and I want the plants to have a natural look.
Thus, I think I still need full spectrum lights, not some bizarre
Glo-lux purple thing.