# Are Lumens Important?



## aquariumrookie (Jun 26, 2014)

Hey guys!
I am thinking about planting my 10 gallon aquarium and I was wondering ahout the brightness of the light.
On my other planted aquariums, I run high wattage and high lumen CFL lights. But on this 10 gallon I just happened to use a flourescent t8 light fixture. The bulb I am using is an 18 inch, 15 watt, 6500k, t8 bulb with a lumen rating of about 500ish if i am not mistaken. Compared to my other aquariums, my 10 gallon is the dimmest. Will this influence the plants i choose for that aquarium or no?
THANKS!


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## TropTrea (Jan 10, 2014)

There are various ways of measuring light output. The most common is the Lumn which is based on the sensitivity of the human eye. Since the green part of the spectrum is the most sensitive to the human eye this part of the spectrum is rated the highest on the Lumn ratings while blue and red light are rated less. The most common meters for evaluating light for plants are the PAR meters. The PAR meters rate all light equally throughout the visual spectrum and there fore give a better comparison. But in reality even the PAR meters are are not ideal because they rate red green and blue equally while plants do need red and blue light they have very limited use for green light. 

The color temperature of 6,500K is normally in the range of what is considered daylight. If you were to in the shade at mid day an object should appear the same to you as it would with a 6,500K light source. In the case of deep water plants of plants that from areas that are shaded a majority of the time this is probably the most ideal color temperature bulb you can get. However plants that are areas where they get direct exposure to the sun and are only getting a minimum of light filtration through the water a lower K temperature may give better results as it should be delivering more red light. When I used florescent lighting on planted tanks I found the best results from mixing a 6,500K and 5,000K in the fixture. 

Going back to your tank you have a 18 Watt 6,500K bulb which is roughly 1 1/2 watts per gallon. Yes you should be able to grow plants with this amount of lighting but you will have to be selective in the plants you pick. Crypts and Anabus I think would be wise selections for your tank. Ammania, Ludwigia, Rotala's should probably be avoided.


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## Yo-han (Oct 15, 2010)

A great explanation about light from troptrea, although I don't agree on the plant selection. The 'difficult' plants are only difficult because they need more CO2, most can do with very little light in my experience and most problems people have are due to too much light, not too little! Besides that, most commonly available Ludwigia and Rotala are quite easy. Check the plantfinder!


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## TropTrea (Jan 10, 2014)

Yo-han said:


> A great explanation about light from troptrea, although I don't agree on the plant selection. The 'difficult' plants are only difficult because they need more CO2, most can do with very little light in my experience and most problems people have are due to too much light, not too little! Besides that, most commonly available Ludwigia and Rotala are quite easy. Check the plantfinder!


True Ludwigiia and Rotila have many species with different lighting needs. Generally speaking but not always the more red in the plant the more light required. But the plant finder is good place to go for specific species information.


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## raminaniston (Dec 24, 2014)

Recently, my home remodelling has completed from denver renovations and I have bought 10 gallon tank. Right now I am using two 20 watt CFL spiral bulbs in 10 gallon tank. They function relatively well, and light distribution is good enough. It is focused in two areas.


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