Actinic Lights

I have 2-400 watt metal halides which really brightens up my 150 gallon but it is the actinic that I run before, during, and after the halides come on that seem to bring out the color in my corals and fish.  I say if you have them then leave them on.

Tim

Interesting.  I also was under the impression actinic were for looks more than anything.  What spectrum are the white lights?  Personally I don't like my 10k MH w/o actinics... to yellow for me.  On the 55g I have 10k PC and they are not nearly as yellow looking but I still like the looks of actinic's on that one also.

Weimers wrote: We were told the blue lights didn't "do anything" for any of the inhabitants, other than let them know it's almost time for "sunrise" and "sunset."

Where did you hear that???

Adam

So that's why the ocean is blue!

Does anyone have access to a light meter or something that is capable of measuring the wavelength of the lights on our aquariums?

Rodney,

I have a photometer, but it doesn't tell you what you are receiving for different wavelengths.  I've often thought of buying one, but never have.  May be a better club purchase to have.

Adam

Intensity vs spectrum quality...  not a new debat but it's still being debated.  The way I understand things is the PAR rating on the bulbs is the key.  The 6500k Iwaski is supposed to produce one of the highest par ratings of all MH.  It is rumored that the 6500k Iwaski produces a greater coral growth than other bulbs for that very reason.  The 10,000k XM's are supposed to be just under the Iwaski's so now we have a "good growth" bulb in the 10,000k flavor.  The 20,000k bulbs are said to produce the slowest growth rate due to the lower par ratings...  it would seem to me if the bluer spectrum was really important to the corals that the 10,000k & 20,000k bulbs would produce more growth than the 6500k bulbs.

I understand the lighting corals get in the ocean is dominated by the blue spectrum but when it comes to photosynthesis (and that is what it all boils down to) all spectrums of light play a key role.  IMO, Since our tanks are not 20' to 60' deep our corals benefit more from a full spectrum bulb than a actinic.

I agree painted bulbs... 7100k PC etc will cause a drop in lighting out put.  I was happy to see the "true" actinic PC's come out. 

I run my 110g lighting schedule like this... 12:00pm actinics on... 1:00pm MH on...  9:00pm MH off...  10:00pm actinics off.

For the lazy, here's some quotes from that article by Dana Riddle:
(the lamps compared were a 4000K philips bulb ($20) and the Sunburst 12000K bulb ($75))

This experiment’s results suggest information potentially valuable for hobbyists - that rates of photosynthesis were essentially the same under these two distinctly different light sources. Other than aesthetic value, there appears to be no advantage, photosynthetically speaking, in using high Kelvin lamps.

The implication of these results should be of interest to hobbyists; it suggests that lamp selection (with due regard to lamp intensity) may be based on appeal, whether that is price or the "look" it gives to a tank, without fear of hindering photosynthesis. Economy-minded hobbyists and coral farmers may find this especially useful. It appears that light intensity and relatively simple light measurements alone adequately judge lamp efficiencies within the context of zooxanthellae photosynthesis. This should not be construed to mean that all light sources are adequate for reef aquaria use.

I think that it has yet to be proven that "blue" or "actinic" light actually stimulates coral growth or increase coral health.  I know people (like Marc Weiss) have stated that 420nm light increases coral growth, but I think this is mainly marketing.

In fact I have read many acticles that have shown that Acropora actually grows faster under 6,500K lights than under high kelvin lights.

And although I had not read the article by Dana Riddle I agree with what he said (thanks for the quote Jon).

I strongly believe in blue light, because of it's importance to plants.  Yes corals aren't plants I know.  But I have recorded photosynthesis rates in corals before, and I am sure they are using blue light to excite electrons in the chain.  I bet I have some nifty graphs at home, I'll look later.

However, get this, if you have enough bright white light, then I guess you wouldn't need blue light because you may already be running at full photosynthetic capacity.  I just don't think many, if any, of us have that much light. 

Aside from photosynthetic properties, and asthetic pleasure, I still think blue light can make a tank look more "real".

Adam