What's the diff?

[stusclan]

Did my yearly changing of the bulbs - even though I put a new bulb on the sw tank 4 months ago (I remember better if it's at the beginning of the year. So my question is, what is the difference in a 40W 10,000K bulb and a 40W 18,000K bulb? I put the 18,000K on the tank, but don't know the difference. Lighting has me confused.

[electrikat]

I beleive the higher the number the more blue the spectrum is. For example with a 10,000k you would also need a blue actinic with it but with a 20,000k you would not because the 20's have a heavy concentration of blue waves.

[JG]

The K refers to Kelvin which is the SI unit of temperature. The higher the temperature the more blue light is produced. Blue stars are hotter than red giants. Yellow- green stars ( like our own) are sort of middle of the road temperature wise. Blues would have a higher Kelvin value than a red.

The sun produces full spectrum. Blues are shorter wavelengths of light and can reach the lower depths of the ocean ( or tank) since they are not absorbed by the water as readily as the reds. This all has to do with the bonding structure of the water molecules and the molecular size.

I'm a science geek - sorry if I bored you to tears.

[stusclan]

That's okay - I'm an elementary science geek. I teach elementary science to grades K-6. Not much need for Kelvins at this level. I'm more into physical science and environmental science. Lots of fun, but I really don't understand the upper level" stuff like light!

So, I guess I'm better off with the one 18,000K for now.

Thanks for the help.