Re: Watts per Gallon

["S. Hieber" <shieber at yahoo_com>]

Gordon wrote:
 
> questions about the whole "watts per gal" idea in tank lighting.
> I'm not an electrical engineer, a mathematician, or a botanist, so
> what I'm
> thinking is most likely wrong, or something like that :)
> Numerous websites have formulas to calculate how many "watts per
> gallon"  of light you need to grow low-mid-high light plants...
 
> The questions I have are:
 
> Isn't watts a rather unreliable measure of light output?  I mean, a
> 75 watt standard incandescent puts off as much light as a standard
> 20 watt cool white fluorescent, or a 13 watt compact fluorescent 
> twist-bulb.  Which wattage do the formula's speak of... 
> I assume they mean watts fluorescent (since
> that
> appears
> to be the most popular)?
> 
> Are there any formula that use something more related to actual light
> output, like lumens or candlepower?  Or formula that are calibrated
> to
> the
> wattage to light output ratio for standard fluorescent bulbs (can't
> afford
> the power compacts yet).

I think Wayne basically said the answer is yes and no.  The math is
there but not all of the input data.

If you're not ready for PCs, are you ready for CO2?  If not, then your
questions might be somewhat simpler.  Why don't you post what equipment
you have, or expect to get, in terms of aquarium set up, whether you
expect to give attention to the tank every day or just once a week or
once a month, what kind of plants you might want to grow, and some of
the folks on this mailing list can then propose some lighting options
for you.  

Even if you want to do all of the math, all of the imput data is hard
to come buy, especially for more than jsut one or two potetntial
setups.  So to do calcs, you'll need a few really big assumptions. 
What gallon measurement should one use anyway -- nomimal? actual?
actual including/excludintg substrate displacement?  What about
distance?  You can fine tune here to your heart's content and still not
have happy plants.  And you can grossly tune and have very happy
plants.  So you might as well try some advice on for size first, eh?  
;-) .

JMO,
Scott H.

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