Tex Gal

This is hard for me to understand, but the graphs help. Just getting info like that on bulbs is difficult and in some cases impossible. After my trip today down LED lane it is abundantly clear that all 6500 kelvins are not created equal, (or any number kelvin).

Growing plants without algae is a challenge with all it's variables, but who cares if the tank color looks horrid. I agree with AaronT that it's more about clean tanks, light and nutrient balance and flow than light spectrum when it comes to algae.

Newt

Yes, to what AaronT said about what causes algae. Kelvin really doesnt play a role - and kelvin is not a spectrum - its a color temperature (CCT). What can possibly play a role in producing algae is the photoreduction of iron by blue light (in the nanometer wavelength; a part of the visible spectrum) that can breakdown the chealant and render the iron 'free'. This is in Diana Walstad's book.

We humans see the bulb's light as a single color created by the combination of all the colors of light the bulb outputs in the visible spectrum (the spectral output graph). We give this single color a Kelvin rating based on the color we see and equate it to the corresponding color temp along the black line in the chromaticity map. Its not very accurate especially after the marketing department does their thing.

Exactly right about one kelvin bulb not being the same as another. Many are marketed as a certain K when they are really not. Like the GE 9325K. A Sylvania 6500K bulb can have a very different spectral output from a Philips 6500K bulb.

rod

Thanks for the explanation. I got a free acitic bulb from a friend and tried it over my planted tank. I ended up with strange algae, never knew why. It makes sence now.

gr33nthumb

That is some excellent information. The chromiticity map is spot on as it shows the big picture per say, taking some confusion out of lighting. thanks newt!

Newt

updated info for further clarification post #12

XJfella95

This post has really come a long way. Very good info.

There really is no need for any blue light other than to satisfy aesthetic appearances. In my opinion a cool white LED would look nicer than a blue LED any day.

After 2 weeks of having the blue light timed only for 4-hours in the evening instead if 14 (all night) my hair algae has subsided and is definitely going away, along with what was left of my GDA and green water.