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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

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 
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 
resort.  I have found that 100K bulbs are not always as pleasing to the eye 
create more light in the blue ranges than desired by themselves.