Tell Me About The Kelvin Ratings

[Ilya]

I've got a 22 gallon. And I bought a new fluorescent tube with 18,000 kelvin. My previous tube had less. Anyhow. What do you think I can grown in 18,000 kelvin? It's a 19" tube with 15 watts.

 

[nry]

Kelvin is to do with colour temperature, generally kevin ratings much beyond 7000 are more suited to marine aquariums. Do a Google search, it will likely help you find out more.

 

[DevUK]

Theres also a great sticky thread here that describes a lot of aspects of lighting, including the colour temperature (kelvin)

 

[George Farmer]

18000K. Sounds like Hagen Aqua Glo or Power Glo. Both are ok for plants. Power Glo is brighter.

K isn't too important. Plants aren't that fussy, except extremes i.e. actinic.

 

[JamesC]

Don't get too hooked on Kelvin as it doesn't really tell you that much. You can have two different bulbs rated at 6,500K and one can be great for plant growth and the other one crap. A lot of people, including me, are raving about the GE 10,000K bulbs which are great for plant growth and have a great colour too.

Coming back to you 18,000K bulb, I think it is maybe too high for plants and more suited to marine setups where more blue light is required. If in doubt about buying a tube for plants then go for an aquarium one that says it is designed for plant growth and you won't go far wrong. It's then just a matter of finding one or a combination that is pleasing to your eye.

James

 

[Ilya]

I have to find a two bulbed lighted top!

 

[Ilya]

Wait. If that's the case. Why don't I just use a single 60 watt bulb?

Would two 100 watt light bulbs do the trick?

 

[George Farmer]

You mean incandescent tungsten bulbs?

They are very inefficient, so will give you the equivalent of around 15% that of T8. So 100w tungsten would be 15w T8. And reflectors would be tricky. They get too hot too, that's where most of the energy is wasted, via heat.

Colour temp. wise they are very low, so don't have much blue. Still OK for plants though.

 

[Ilya]

Alright. Well, I also have a regular 13W fluorescent light bulb. Would that along with my current fluorescent tube work better?