Re: Watts/gal

> From: Peter Konshak <pkonshak at fiat_gslis.utexas.edu>
> > From: "shaji (s.) bhaskar" <bhaskar at bnr_ca>
> > Date: Thu, 20 Jul 1995 11:01:00 -0400 
> > Subject: re: Watts/gallon guidelines 
> > 
> > There are people who keep plants with 1 watt/gallon of wide-spectrum lighting
> > (for example, Kevin Osborne, though he is not in much favor on the Internet.)
> I have a similar setup.  I have 80 watts over my 75 gallon tank, with 
> great results.  I have one 40 watt GE Chroma 50 and one 40 watt Growlux 
> Wide Spectrum.  I've been meaning to write about how well this has worked 
> for me, but....  :)

What plants are you growing Peter? Crypts would do ok as well as Java moss,
H. poly, H. diff. but growth rates would be lower I bet. ;-)

> From: nguyenh at nosc_mil (Hoa G. Nguyen)
> >From: "shaji (s.) bhaskar" <bhaskar at bnr_ca>
> >In my opinion, there is no hard and fast requirement on lighting.  The
> >wattage needed depends, among other things, on:
> >
> >1. The depth of the tank.
> I agree, and this depth is very important.
> >
> >Overall, I agree with you that it is difficult to come up with a
> >formula for how much light is needed.  I'm not so sure that the
> >larger tank = less watts/gallon pattern that you noticed in Amano's
> >book can be generalized.
> >
> Don't you think that a generalization can be made from fact 1 above?  All
> other things being equal, the volume goes up on the order of the cube of the
> depth (assuming that tanks tend to be of the same general shape, i.e., you
> increase other dimensions as you increase the depth also).  This is a very
> very rough generalization, but I can see how less light is usually needed
> with larger tanks from this fact.

I think what Shaji is saying that the rule for desired wattage of fluorescents
is not linear with volume which is implicit in a watts/gal.  measure however it
is a "valid" first order approximation for tanks which often are 18" in depth.
The rule should be:

wattage = ((K1 + K2 x depth + K3 x depth**2) x width x length)

K3 is small compared to K1 and K2.  A tank with zero depth still needs light,
hence K1 is not zero!

New subject: pronunciation of plant names

Listening to George on tape made me realize how much differently I pronounce
some words like Hygrophila (maybe it's George who's different ;-) I say it:
HIGH - grow - fill - ah and George says it high - GRAW - fill - ah.  Anybody 
besides George and me know the correct pronunciation.  Maybe it's because I'm 
a Canadian, eh?  ;-)

 - Steve