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Re: lighting for a 75 gallon.

In a message dated 06/29/2001 2:54:28 PM Central Daylight Time, 
Aquatic-Plants-Owner at actwin_com writes:

<< 
 I just purchased a 75 gallon Oceanic Tank and stand. 
 I’m now buying the lighting system.  I know I want to
 keep some carpet plants in the front of the tank. 
 Either Echinodorus tenellus or dwarf sag and
 hairgrass. Maybe pearlgrass or sunset hygrophila.  I
 haven’t committed to other plants yet but I don’t
 think I’ll be keeping many really high light or red
 plants.  I will be running CO2.  I have decided to go
 with AH Supply lights.  Now I’m wondering what lights
 to buy.
  >>

Lets look at some of the the basics here.  First off
you have a 75 gallon tank with a surface area of 48"
X 18 inches.  With the 75 gallon total volume I'd normally
recomment 225 watts maximium initial light.  

Looking at the AH fixtures to get near the 235 watt
total you would either use 4- 55 watt units for 220 watts
total or 2 96 watt units which would give you 192 watts
total.

The draw back with the twin 96's is that they are about 36" long 
and would overlap in the center giving you a potential hot spot.
With the 4 55 wat units they could be much easier devided up
to give you even lighting over the entire tank.

Next comes the selection of bulbs.  My personal therory is a combination of
color temperatures helps assure a better coverage over the entire light 
spectrum
which helps asure better color viewing as well as lighting that covers all
the prefered color temperatures the plants require.  For standard florescent
bulbs I find that either a combination of 50K and 72K or 50K and 100K do a
fasntastic job for me.  With the selection of bulbs that AH has available
I'd probably select a pair of 53K bulbs in the front and a pair of the 67K 
bulbs in
the back.  In the event that the higher Kelven temperatures may be deficient
in the future I'd consider replacing one of the 67K;'s with a 100K only as a 
last
resort.  I have found that 100K bulbs are not always as pleasing to the eye 
and 
create more light in the blue ranges than desired by themselves.

Dennis