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Re: Watts/lumens (again?)

On Fri, 22 Jan 1999, Bob Dixon wrote:

> Okay, guys, help me out here.  When we talk about two watts per gallon, are we
> talking standard florescents?


> By standard I mean those 3180 lumens 40 watt
> tubes that come standard on most light fixtures and are sold in grocery store
> everywhere.  They offer 79 lumens per watt, or thereabouts.  So if I for
> example put two of these over a 40 gallon tank I have two watts per gallon, or
> about 158 lumens per gallon.  But re we talking two 40-watt bulbs without
> decent reflectors?  Or are we talking about light fixture with a reflectivity
> of 50%.  Or are we required to get something like "Coilzak", which has an 89%
> reflectivity minimum guarantee?

Normal reflectors.  White, been used for a while, maybe a little dirty.

> If I use a highly reflective fixture, can I
> say that I have inceased those 158 lumens by 90%, because all the light that
> was going up instead of down is now heading properly into the tank?  Which
> would put me at 300 lumens per gallon.

Nope.  Don't do that.  I'll guess (Erik O. probably knows for sure) that a
practically perfect reflector would only give you a 30% to 50% increase
over an average reflector.  Besides, remember that lumens measure the
brightness of the light as perceived by human eyes.  Lumens aren't
necessarily very meaningful to plants so there's probably not much point
to splitting hairs.

> And then what happens when we go to the local lighting store and find Philips
> ultralumes, which are visibly way brighter than standard bulbs?  Or are we
> already talking about the enhanced output bulbs when we say that we have two
> watts per gallon?

Nope.  Normal output.

> Okay, I know that this is just a rule of thumb to simplify our tank planning
> and layout.  Yet I read numerous discussions here about alkalinity, pH,
> ferrous compounds, EDTA, etc. ad infinitum which seem to get really really
> detailed, certainly more detailed than most of us need to get a handle on the
> basics.  Now I want some more guidelines.

So we go overboard on chemistry and that should justify our going
overboard on physics, too?  (implied smiley).

> I have three tritons over my 30
> gallon tank.  They look twice as bright as the bulbs that came with the strip
> lights, so do they count as 60 watts each?

No.  Maybe the ones that came with the strip light should count as 15
watts each.

> I am setting up my 55 to have one
> F40/T12-75UL, one F40/T10-50AX, and two Interpet Triton 40 watters.  All of
> these bulbs are way brighter than the standard F40/T12 bulbs. Am I overkilling
> it?  And do you know of a website for Philips or Interpet where the lumens
> ratings for these bulbs are posted?  Or an address I can write to?

Four Chroma50's over a 55 gallon tank produces a bright tank.  This batch
will be blinding (IMHO, YMMV, we all see light a little differently, etc,

I've used Philips Ultralume and Advantage bulbs.  I love them for both
longevity, brightness and color rendition, but I relegated them to the
fixture over my workbench.  I was using four 5000K bulbs (Ultralumes and
Advantage, mixed over my 55) and all of my plants started accumulating
damage on unshaded areas of leaves.  I don't know for sure why that
happened but I found after getting technical assistance from Philips that
the "red" peak in both tubes (these are triphosphor tubes, so their
spectra consist of three separate spikes, one green, one blue-violet and
one orange-red) was actually not a true red; it's orange, and mostly below
the wavelength where plants' red-sensitive pigments operate.  *If* that
was the problem, then your combination of the Ultralumes and Advantage
bulbs with the Tritons probably will avoid the problem.  If I recall
correctly, the red peak in Tritons is a true red - it is at a longer
wavelength than the "red" peak in the Philips tubes.

Philips has a large web site and the technical specs of some of their
bulbs are included there, but I don't have the URL.  They employ a firm in
the US (Philips is a Dutch company) to provide technical support via 800
number and they were quite helpful and friendly.  I don't have the 800
number.  Could I be more helpful? (place a sarcastic smiley here).

Roger Miller
er, I think.