Lighting Questions

Discuss specific plants, general plant care, help setting up a plant tank, rare plants, and general help
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Chris
Posts: 80
Joined: Tue Jul 07, 2009 9:12 am
Location: Fairbanks, AK

Lighting Questions

Post by Chris »

How many watts/ gallon are recommended for tanks with & without CO2 to grow a wide variety of plants?
Is there a difference?

I'm looking at purchasing lights for a 5.5gal, 20L, 20H, and 33L.
Up till now I've been using single T8 bulbs, it's time for an upgrade. :)
ingg
Posts: 2418
Joined: Fri Feb 16, 2007 1:29 am

Post by ingg »

For a second, let's ignore the 5.5g to provide a simpler answer.

For the others, a range around 2 wpg can avoid high tech CO2 use, yet grow most plants. A range of 3-4 wpg should grow about anything, but will really need the balance of CO2.



Now....The 5.5g is a tank that shows why WPG is a bad rule to use. It will require more WPG than the others for the same king of lighting levels in terms of what it'll grow. I'd peg a tank this small more in the 5-6 WPG range for medium light, and closer to 10 WPG for high light.



Without getting totally geeky on it (and in the few minutes I have to type here) very small tanks and very large tanks break the rules of WPG. Small tanks - say under 10g - needing more, large tanks - say over 75g - needing less.

It is more accurate to look for lumens per square inch of tank floor, and even more accurate to use PAR since there is such a wide variety of lighting solutions (and relative outputs of lumens per watt) out there. Depths of tanks also are a factor, thought more rarely, making PAR reading the best...
Dave
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