# Actinic lightning



## taylor775 (May 11, 2006)

Hi Guys/Gals,

Question in new to the Aquarium plant hobby. I had a powercompact dual strip light one with a normal light and one with a actinic light. Is using the actinic harmful to plants or no.


----------



## akos (Dec 14, 2005)

I don't think actinic is harmful, but lots of folks say that its not very useful for planted tanks. Basically its the wrong wavelength for plants to utilize it for energy. Prob. best off swapping the actinic tube to something in the 8K -10K range.


----------



## jbierce (May 11, 2006)

Plants won't get much out of actinic lighting, so it's not really worth having unless you like the look of it. In deeper waters the red end of the spectrum is mostly lost, which is why most ocean life have adapted to utilizing the blue spectrum so efficiently. While these deepwater creatures can also grow like weeds under normal daylight tubes, our freshwater plants simply aren't adapted to use only one part of the spectrum. The best tubes to use are the 5500K-6500K for fast growth, but many people like the looks of the higher spectrum (8000K-10000K).

JBierce


----------



## jude_uc (Feb 7, 2006)

Besides not contributing to the overall growth of your plants, I think the plants look better without the actinic lights. My history has gone from 10,000/actinic --> 6,700 --> 10,000. So far, I'm liking the 10,000 the best because it makes my dwarf blue gouramis look amazing. 

-Adam


----------



## joseney21 (May 11, 2006)

i know color wise things look better (imo) in the 10k-14k spectrum, below 10k is too yellow but then again i only have experience messing with lighting in my saltwater reef (just starting to setup my freshwater planted). same principle applies though, things grow better in the 6500 range but look better in the 10k range. for a saltwater tank the actinics make the corals fluoresce, i've never heard of freswater plants glowing so it would seem the actinic is useless in this application...this all just my speculation though, lol.


----------



## taylor775 (May 11, 2006)

Would it actually harm the plants if used.  I have heard that it doesnt affect the plants in any way.


----------



## jude_uc (Feb 7, 2006)

No, the actinic doesn't harm the plants at all, it just doesn't do anything for them. I had a half and half for a while and the plants grew, just very slowly.

-Adam


----------



## jbierce (May 11, 2006)

No, plants aren't harmed by actinic lighting; in fact in a small way it actually helps them. Like all life forms that use photosynthesis, plants utilize light from mostly the red and blue parts of the spectrum. Sunlight has an abundance of both, but water filters out the red faster than the blue. Because of this, deepwater photosynthetic critters don't see much in the way of red light; so over time they've adapted to more efficiently use blue. That's the reason behind actinic lighting in saltwater tanks where deepwater corals are kept. Freshwater plants live in more shallow waters (or out of the water) where there's a good deal of red available. Giving them actinic lights will give them part of what they want, but not all of what they require. It's not a case of harming them, but rather a case of inadequacy.

JBierce


----------



## Salt (Apr 5, 2005)

I am one who disagrees that actinics "don't do anything for plants." Rather, if you have adequate lighting in the 5500 - 10000K range, then I believe actinics make very good supplemental lighting. Plants _do use_ light in that wavelength. In my own experimentation, I have found that plants respond better when _supplemental_ actinic lights are used. There is a speaker in the AGA 2001 DVD that also reports similar findings.

Personally I have a 150W 6500K metal halide with two 32 watt actinic power compacts. The actinics simulate the backdrop of a blue sky and produce very natural looking lighting.


----------



## jhj (Feb 18, 2006)

I have been told that if the PC fixture is 260W and half is actinic, you basically only have 130W of lights for your plants.

The good news is that replacecment bulbs are not that expensive, look on ebay and you can find 4 6500k bulbs for under $30


----------



## jbierce (May 11, 2006)

That's not really the case, since plants do actually use actinic lights; it's just not their ideal spectrum. Plants will utilize them much better when mixed with full spectrum tubes. If you're buying new lights then by all means buy daylight and not actinic, but if you already have actinic lights you won't be harming your plants at all. In fact they'll be able to use them to some degree.

JBierce


----------



## jude_uc (Feb 7, 2006)

In Tom Barr's write up, it seems that red light stimulates glucose synthesis whereas blue light stimulates starch degradation. Also, since the photosynthetic range is 400-700nm and actinic light is at 420nm, it's at the edge of the absorptive range. Again, actinic light doesn't hurt, but both from my experience, and my reading of the Barr's collection of research, actinic light does little to aid the synthesis basic structural materials. However, in the end, perhaps it doesn't really matter too much and you should just go for what looks good.

-Adam


----------

