Actinics, Algae and understanding Kelvins

[Lebowski_]

So I have always been told, since I started in this hobby, that actinics don't provide the proper light for algae growth.

However, looking at Action Spectrum for Photosynthesis (below), it would seem that plant material would thrive under the 420nm actinic bulbs commonly sold to hobbyists.

So does actinic light actually aid in algae growth?

Does the algae within the tissue of the coral also correlate with this chart?

And finally, I've been told that the Kelvin rating on bulbs is only important in how we see corals, not with how they grow. From what I've been told, the colour temperature is what is actually important. Is this true for our coral as well? And if so, what use does Kelvin have and how should we choose our bulbs?

Thanks for your time.

 

[billsreef]

That nice peak of the actinic happens to be good for our corals because it matches the photosynthetic peak of blue part of the spectrum. The idea that it wouldn't also grow algae is kind of silly. That said, many of the nuisance algaes grow better with more of the red peak, hence where that silly idea comes from that blue light won't grow algae

With the color temperature, the Kelvin rating is essentially the color temperature. Unfortunately for us, there is little reality between actual K ratings and the stated ratings by bulb manufactures. Best is to look at the actual spectral charts.

 

[kentuckyclowns]

Another set of factors are the different types of chlorophyll cells. Simply looking at "plant spectrums" will not show you the difference between plants and corals. Both have chlorophyll cells but, as mentioned above, the plant version prefers (not requires) the red spectrum. The coral cells prefer and require the bluer spectrum for tissue health and in turn growth. The biggest thing to eliminate or reduce algae growth is a lack of nutrient presence; specifically phosphates.

 

[Lebowski_]

Thanks for the replies!