# CFL for a 55 gal



## Joshie (Sep 5, 2011)

I've had this set up for about 2 years now. At first, I didn't pay much attention to the different kind of bulbs. Lately I have been studying more into them to find out that Kelvin, Lumens, and specific wave length that are good for good plant growth.
I would like to try and shoot for moderate to high light for my tank. 
as of now I am a bit confused on which watt do I pay attention to, the out put or the wattage that the bulbs are using. The out put is about 100 watts and only using 23 watts. I have 7 of these on the tank. the box said it put out 1600 lumens each bulbs and they are 5000k. I am not sure if this is good for the plants, since it's suggested that 6500k are better and it's kind of hard to find them. 
Then I read up on about how plants uses the red and blue part of the light, and since the higher the kelvin, it's closer to the blue, how can I get more of this red part? 
At this moment I am in a cluster of confusion and I am open for any suggestions, although i would like to keep it only using CFL bulbs.


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## Michael (Jul 20, 2010)

Joshie, welcome to the confusing world of lighting!

First of all, ignore lumens. Lumens are a measure of how bright the light *looks to the human eye.* This has nothing to do with the light that plants use for photosynthesis, it is possible for a light to have a high lumen rating, and be almost worthless for plants.

Second, the "output" wattage and the "use" wattage are just a way of comparing CFLs to incandescent bulbs. This is a guide to consumers, all you need to know is the use wattage.

Now, most of our information about CFLs comes from hobbyists measuring their output with a PAR meter. This device measures the light that is useful to plants, not necessarily the light that looks bright to humans. DFW APC has a PAR meter that members can borrow to measure the light in their tanks.

Both 5000K and 6500K CFLs will work for planted tanks. Most people like the appearance of 6500K better, but that doesn't matter to the plants.

I use CFLs on several of my tanks, and from my measurements I would say that seven 23w CFLs over a 50 gallon tank is a lot of light! Surprisingly, it makes a big difference if the CFLs are mounted vertically or horizontally. The vertical position produces almost twice as much light. Reflectors also make a big difference--a nice shiny curved reflector puts a lot more light into the tank.

My guess is that you already have plenty of light. But you can measure it yourself with the PAR meter. There is a sign-up thread for the PAR meter in the DFW forum, or you can send me a PM.


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## Joshie (Sep 5, 2011)

ohhh thank you, all of mine are horizontal since I kind of pimp out the florescent hood that came with the tank. I thought about mixing 5000k and 6500k bulbs, would that be okay?


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## Michael (Jul 20, 2010)

Mixing them will be fine.


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## Joshie (Sep 5, 2011)

thank you!


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