So, Actinics are just for "THE look"?

I am running 260W of compact fluorescents (4 X 65) over a 100 long tank.
I want to get a good deal of growth rather quickly without having to add another fixture. From what I've read, actinics are more for the look than actual photosynthesis. If that is the case, why not pull the actinics and run more 10,000k or 12,000K bulbs?
Would going to a few 6500K bulbs be even better for growth? I've heard it will increase algae growth, though...

 

acintics are alot more than just looks, their your spectrum lighting, can be much better explained by one of the guru's here

 

Actinics as i understand feed the corals etc, with the blue lighting spectrum required for photsynthesis, the blue light is what penetrates the deepest in the water, hence where the corals would be,somewhere along them lines anyway... i have 2x39watt 22000k in my 55 hope this helps

 

You have very low-lighting for that tank... you probably want to look at getting a different fixture. For comparison... I am running 380w over a 72gal.

 

260w in 100 gal isn't terrible, you prolly won't wanna get most corals. whatever you do have or get might live, but won't grow very fast if at all unless you upgrade or add another fixture. alot can thrive in 4watts/gal more can thrive in 5watts/gal now your at 2.6w/gal. actinic is needed for spectrum. your daylight bulbs have a color temp. Kelvin which is basically simulating whatever depth your aiming for. get another pc fixture or a 200w T5 fixture to go along w/ your current PC's.

 

Agree with nunch...260w OK as long as you are happy keeping your soft corals. Speed of growth not important as long as you remember you are in this for the long run. As long as corals are fully expanding and look OK, you are doing just fine.

Many report actinic light promotes the growth of Zoaxanthellae algae, essential for the growth and well-being of all photosynthetic corals and inverts ...if so, makes it even more important for a low light tank.

Most important to you is keeping your water absolutely crystal clear to maximize effect of available light. Use of a surface skimmer and additional water filtering must be seriously considered.

I only have 24w (50-50) over my 12 gal NanoCube and it looks great.




Good luck!

 

Wattage is a terrible measurement of light. For example compare a 500w Halogen to a 150w MH. The 150 MH will put out much more usable PAR for the corals while the Halogen is basically a heat lamp.

Although PC's are efficient the problem is in the reflector. The bulbs are so large that they suffer from light re-strike. A T5 set up with ~40% less wattage would put out much more light given individual reflectors.

Actinics are primarily for aesthetic. If you want the most growth you want to the most PAR. a 6.5K bulb will put out significantly more par than a Blue Actinic... You tank will also appear "yellow" and coloration will not be as nice.

6.5K have enough blue in the spectrum to properly grow corals, but not always to illicit pigmentation or represent the pigmentation of the corals the best.

Something else to consider, with PC's you will be stuck with Softies and LPS, most of these corals are from deeper water where the light is bluer.

So to answer your question, yes Actinics are for aesthetics... but trying to maximize PAR with PC's is futile IMO. A well balanced spectrum including Actinic bulbs will see better coloration and minimally less growth. I would suggest focusing your efforts in water quality to increase the effect the lights will have. Lower nutrient levels and less light is needed.

 

PCs are crap anyway IMO. Upgrade right away. The actinic is what provides the micro algea living in the coral to grow. While increase the color of the coral.

 

From wet web media:
<Higher K bulbs are better for what most want for aesthetics nowadays. Corals do better under the 10000K or even 6500K offerings out there. They offer more intensity in the usable spectra involved. The actinic and blue bulb mentioned will do little or nothing towards sustaining photosynthetic organisms.>
(I added the highlighting)
AND later, same article:
Basically, I know that whiter light is better for standard photosynthesis (plants especially), but many corals inverts exist 10,15,20ft down, where very little low frequency white light exists.
<Photosynthesis still occurs the same way, same usable wavelengths of light even though there is less of it, giving a bluer appearance.>

So, it sounds to me that, given the fact that I am using a low level of light,
I should be using lower spectrum bulbs. This should increase the usable part of the spectrum.

Funny how many people swear actinics are needed for Zoaxanthellae algae.

 

It is. I'd attribute most of it to marketing...

One thing to consider is when most talk about Kelvin's in the hobby it is related to Metal halides. LEDs, T5s and PCs have a much narrower spectrum than MH's. Go for a nice mixture, it will hit all ranges of absorption and make your tank look better.

The marginal increase in PAR from a 6.5K PC bulb versus a 10K PC bulb will not cause any real noticeable increase in growth. Placement, Flow and water quality will have a much larger and noticeable effect.

As antonym said, PC's are not a very good light source. They degrade quickly, have poor reflectors, and by design are not as efficient as T5's and MH.