actinic good for plants?

nvision

nvision

what the heck is a pl*co?
Dec 11, 2002
381
1
18
Sunnyvale, CA
jau.smugmug.com
hi all. i've tried doing a search, but have found no relevant results.

basically, i was so thrilled about the recent compact flourescents that i went and bought another unit for my 10g, a coralife 28w fixture. it includes a 50/50 (10,000k/actinic 03) bulb, and as i test the unit right now i'm seeing a very nice, soothing, marine-blue glow in the tank.

while the color is attractive, and with the general consensus that 6500k is best for plants, has anyone actually grew freshwater plants with actinic? i've heard that blue spectrum generally makes plant grow "bushier", and not as tall compared with white light. i'm thinking about trying it out (basically don't want to fork out more cash for an extra bulb, for now). heck, i've even come from a halogen light setup for years. doesn't hurt to try actinic while i'm at it, eh?

though it would be nice to hear of first-hand experiences from others, however. thanks in advance.
 
I use an actinic for a moonlight effect for 30 minutes after I shut the main lights off. For my main lights, I use a 6,500K and 10,000K bulbs because I like a crisp white color. All 6,500K bulbs look too green to me. All 10,000K too blue. I'm just very picky about my lights.
 
the most beneficial spectrum for plants is from 5000-6500K.

I see no reason to waste electricity providing light in other spectrums that wont do any good.
 
I've always wondered how plants react to actinic light. Chlorophyll has a blue peak and a red peak for aborbance. The actinic should target the blue peak exclusively and rather well, and not necessarily be less effective than a full spectrum 5000K. Plants have cholorophyll similar/identical to that of the dinoflagellates in corals (which the lights were designed for), although plants are probably better at using red since red does not penetrate ocean water well.

Has anyone done any controlled (not anecdotal) experiments on plants and their responses to actinic light? I'd really be interested.
 
Plants dont use blue light anywhere near as effictively as algae.

All plants are largely terrestrial in nature and are adapted to using the white spectrum (largely yellow, red, and some blue)

Algae are aquatic and are adapted to using blue first, and white light second.
 
I agree, plants really prefer the red end of the spectrum.
 
thanks for the responses.

i think a plant has reacted to the lighting--wasn't good. i've ran the bulb for a day just to test it, and apparently my baby tears, which has been growing submersed (very pretty) on top of a high rock above the water surface, has drooped down tonight. this may be considered its initial reaction to the actinic lighting, but i couldn't rule out the light as ineffective because i also notice a few new stems that are beginning to grow out, albeit tiny. maybe the plant is just beginning to adjust? i'll let the light run for a few more days and see what happens. i've also read somewhere that plants do use the blue spectrum, but i'm not an expert to verify this. just have to wait and see i guess.

as for algae, i haven't noticed any difference in the tank yet. but having read that actinic promotes algae growth is really disturbing to me.
 
A plants photosynthetic action spectrum shows that relevant intensities of blue and red are about equal, although plants can use a broader range of low wavelength (blue) light than red.

light_fig9.jpg


The key is balance. If you are supplying a great deal of excess in any part of the action spectrum, then algae will be happy to oblige and utlize that light. Algae is a very opportunistic and adaptive organism. They will use whatever light that plants aren't using (as in the presence of a low-CO2 environemtn and high light).

So if your bulb has strong output in the red and green areas of the spectrum, and weak in the blue, a supplemental actinic bulb could definitely help. You're better off finding a bulb that is designed to match the Photosynthetic Action Spectrum (like the Sylvania Gro-Lux) and not try to create that balance on your own.
 
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