# Lights On a 20 Gallon Eclipse 2



## ericpop27 (May 13, 2008)

*Would two 18" 20,000K Coralife lamps on a 20 gallon Eclipse 2 be suitable for growing plants? It seems like most people are recommending lower Kelvin numbers, and though I've read numerous sites about lighting...I just don't understand it.*

*These are the bulbs in question*


----------



## trenac (Jul 16, 2004)

The range that plants prefer is between 5500k-10000k, with 6500k/6700k being most common. When you get into K ratings over 10000k then the bluer the light, which corals like. But plants prefer the red yellow range.

Here is some good reads... http://reefkeeping.com/issues/2006-02/sj/index.php

http://www.aquarium-lighting-guide.com/aquarium_lighting_guide#spectrum

http://www.aquaticplantcentral.com/forumapc/science-aquatic-lighting/723-9325k-difference.html

http://reefkeeping.com/issues/2006-05/sj/index.php

You will need at least 30-40 watts total to grow low light plants.


----------



## LetDiceFly (May 30, 2008)

If you are looking to maximize your lighting there are CF retrofit kits at Dr. F&S designed for the Eclipse hood, could get you up to 64w. I have the Eclipse 1 with the retrofit for the single light. Was a big difference for me 15w to 32w.


----------



## ericpop27 (May 13, 2008)

I am so confused...I keep reading everywhere that plants wanted the blue spectrum.


----------



## Left C (Jun 14, 2005)

ericpop27 said:


> I am so confused...I keep reading everywhere that plants wanted the blue spectrum.


Blue light is necessary for many inhabitants in saltwater because blue light penetrates to the deeper depths where many corals, etc. live.

Most freshwater plants are found in shallower water and they are able to use more of the color spectrum for photosynthesis.

Plants use mostly the blue and yellow/orange/red part of the color spectrum. Here's a simple pic.










There's also other accessory pigments involved in photosynthesis too. Another pic.










Here's the Action Spectrum for Anacharis. Notice where the spikes occur. These are the wavelengths used by this plants for photosynthesis.










Here's the color spectrum graphs for two popular plant lights. one's a 6700K bulb and the other one is a 9325K bulb. Notice where the spikes are. You'll also notice a green spike too. This is for reflecting the green color of the plants and make the plants look attractive to the eye. If you used a light bulb that works well for growing plants, it would be a reddish purple color and it would not make your aquarium look very good.



















Years ago, I tried two 20,000K bulbs in my Eclipse 1 TL fixture. It looked horrible and it didn't grow the plants very well. They were the bulbs that my LFS suggested. They didn't really know very much about planted aquariums and I was a newbie.

Here's some more info about photosynthesis: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html


----------



## ericpop27 (May 13, 2008)

*Thank you! rayer: Now I understand. I'm off to the store to get some plant bulbs. Thank you!*


----------



## ericpop27 (May 13, 2008)

*I purchased two 18" TROPIC SUN lights (5500K). They are extremely bright and the tank looks beautiful. Once again, thank you for the info!*


----------



## Left C (Jun 14, 2005)

I'm glad that you like your bulbs. They are a good choice. I also hope that you understand lighting and photosynthesis a little better. All the information and the links that people gave you are very good.

I like Zoo Med's bulbs. I used to use their Flora Sun bulb with a 5500K, 6500K or an Interpet Triton bulb. The Flora Sun bulbs are a little pinkish and they bring out the reddish colors in an aquarium plus they grow plants well too.
http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+3733+8066+4479&pcatid=4479


----------



## Ulan (Oct 2, 2006)

Left C said:


> There's also other accessory pigments involved in photosynthesis too. Another pic.


Note that Phycoerythrin and Phycocyanin, which absorb in the green/yellow range, are only found in cyanobacteria and red algae.


----------

