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Re: QTL's

On Sat, 28 Nov 1998, Duane R. Menting wrote:

> I have check on a few questions I (and others)had on QTL's(Quartz Track
> lighting ).

 = Halogen

> First they are 1/3 less lumens per watt according to theory compared to
> standard FL's.

Uh, did you mean "1/3 AS MANY" instead?  At any rate...

> This is why I am perplexed at my observational data . I've found
> they(QTL's) to grow plants of many varieties at much faster rates . I
> have 80w of FL's on and 150w of QTL's on the same tanks. The lumens
> should be 2400 for QTL's and aleast 6000+ for the FL's yet the rates are
> slower for FL's.

This does confirm what some others have reported.  I think the reason is
that fluorescents have a narrower spectrum.  Good for the human eye, since
what's cut off is infrared & ultraviolet, which we can't see anyway.
Plants may be able to utilize these far ends. Lumens are weighted towards
the center of human vision response, green, so they aren't necessarily the
best way to measure what's best for plant growth. 

Some other possible reasons for the effects:  Reflector types can affect
50% of the light's ability to get into the tank...  Also, a halogen spot
may have the ability to direct more light to a smaller area..

  - Erik

Erik Olson
erik at thekrib dot com