Got A New Bulb... Still Not Bright At All

[fishwatcher]

I had posted earlier about the plants not growing well. I went and bought a new bulb today, called AquaGlo. It is just 15 watts (none of the others were any hight wattage either), and it is 18000 k. Well, it still is so dull looking, it's actually kind of dark looking. What kind of bulb should I be using??
My other tanks all use the screw-in type flourescent bubls and are just great.
Thanks for the help!

 

[Themuleous]

The only way to get brighter light is to have more tubes. A 15w tube (within reason) will only give off 15w of light whether is 1,000k or 20,000k, so changing the bulb again probably wont do anything. If you can add a second tube.

Sam

 

[fishwatcher]

Oh, ok. Well, what is the "k" factor about? It actually seems the higher it gets, the darker the light seems... ???
Thanks!

 

[Themuleous]

The k rating is to do with the colour of the light produced. Lower K = redder light, higher k = whiter/bluer light. People tend to go for tubes that have a rating of around 6500k for planted tanks. But to be honest the wavelength of the light produced is far more important than the K rating.

Sam