Re: T-8 Lighting construction

> From: mike at microspan_com (Mike Roberts)
> Date: Sat, 20 Dec 1997 06:47:49 GMT
> Reflectors - I read someone's idea on the net of using PVC pipe.  What
> about thin wall 8" PVC cut lengthwise so that three sections would fit
> into a 24" hood.  They would then be lined with reflective mylar and
> each bay would hold 3 each T-8 bulbs.  Comments or suggestions?

I would think a circular reflector would reflect the light right back
into the bulb.  You would be better off with a rain gutter type shape.
Or something that better resembles a parabola. 

> Amount of illumination - I have calculated that 9ea NO 5ft T-8 SPX50
> tubes would, after a 10% dropoff, give about the max number of lumens
> suggested in "The Optimum Aquarium" for a 180 gal tank.  How many
> people have had a tank lit this brightly?  

We have 4 [very bright] 48" 40w bulbs over a 100 gallon tank.  Is this
a 6'x2'x2' tank?  Sounds like it may a little too much.    

> is it better to shoot for a ouput more near the middle of the
> recommendations versus either extreme of the range?

I would start with the middle but leave room for expansion (if that is

> Color temp - after reading and some personal correspondence it seems
> that the 4100k bulbs may be better for plant growth, while the 5000k
> and 6100k bulbs would be better for color rendition.  Any suggestions
> on mixing bulbs?

We use rather high temperature bulbs - a mix of 6500K and 7200K (Ultra
Tri-Lux and Triton).  This gives us vibrant colors and seems to match
standard "daylight" photographic film very well (even though you
wouldn't think so). 

> Does:
> ((4100*6)+(6100*3)/9)=4766.6_
> or does the temp of the color not average out that way?

I don't think color temp cam be calculated.  We've rented "color meters"
from photo rental shops to measure color temp.