Blue Fluorescent Light Question

[AdrianB]

I’m a freshwater fish keeper at the moment but just doing loads of research about saltwater.

I’ve searched but cant find any answer so apologies if this has already been asked but what’s the benefit of the blue fluorescent light in the saltwater tank when in freshwater you only use the white tube?

Thanks,

 

[superman]

blue fluorescent lights are commonly called actinic and are mainly used in suppliment to "white" bulbs. The blue is used to make more colors "pop" and make corals fluoresce more than when under light that only mimmics sunlight. There is photosynthetic significance to the actinic light as well, corals will grow under it, though it is not intense enough to be used by itself. Actinic light that has a lower nm (nanometer) rating like 420 nm is more purple and is farther towards the Ultra Violet end of the light spectrum, while 460 and 480 are much more blue and may not make the corals fluoresce like the 420 nm.

 

[crazyelece]

It is used to supplement the daylight bulbs to be more pleasing to the eye. The daylight bulbs are more yellow than white so the blue is added to give a white light look.

 

[steelhealr]

There is an additional reason which is debatable. The deeper you go in the ocean, sea water filters out reds, oranges and yellows, leaving darker colors like blues and violets. Hence, the deeper you go in the ocean, the more blue it appears. Actinics are theoretically providing the blue wavelength that the photosynthetic algae in corals (zooxanthellae) use to photosynthesize at depth. However, most intense lights in the 10,000-20,000K range provide this blue light wavelenght in their spectrum, hence, the debate on whether it is really physiologically necessary. SOOOOO.....most use it to enhance the color of their corals, which, fluoresce nicely underneath it. SH

 

[AdrianB]

Thanks for the replies, very interesting. Thats probably why the marine tanks I look at in the shops seem to look SO much better than the tropical tanks.

I wonder if theres any benefit of adding one of these to a freshwater tropical tank?

Am I right in thinking some people dont use the white/blue tubes but a completely different form of bulb lighting?

 

[RoyalGrammaPrincessHannah]

Thanks for the replies, very interesting. Thats probably why the marine tanks I look at in the shops seem to look SO much better than the tropical tanks.

I wonder if theres any benefit of adding one of these to a freshwater tropical tank?

Am I right in thinking some people dont use the white/blue tubes but a completely different form of bulb lighting?

Yes some people use VHO, PC or T5 fluorescents, and commonly metal halides for the corals requiring more intense light. Not all people use actinics. There are many debates going on about whether actinics do support photosynthesis. You really just have to read for yourself and decide whether or not you believe any of it.

 

[AdrianB]

Thanks for the reply princess, I'm not sure what VHO, PC or T5 fluorescents are so more research for me! Although the tank I have in mind will contain only live rock and fish at least at this stage of planning.

 

[Navarre]

If you wish to keep only liverock and fish then a couple of actinics alonside standard dyalight tubes will be sufficient to bring out the best of the fish's colours

I would hesitate when adding deep blue lights to a freshwater tank as this is totally alien to them, marines are equiped to shield themsleves from the increased UV given off by the blue light but im am not sure if freshwater plants and animals would have a way of blocking out the higher UV spectrum.

 

[AdrianB]

That’s a good point I think I might stick with the lighting I have in the freshwater.

Thanks for the responses.

 

[Aquascaper]

In addition to the points above:

Running Actinics give you the chance to 'step up' the lighting on the tank. Instead of going straight from darkness to bright T5 or Halides, which can potentially stress the fish, inverts and corals, you can do what I do:

Darkness
Actinic
Actinic + T5
Actinic + T5 + Halide
Actinic + T5
Actinic
Darkness

This provides a much more natural light cycle IMO and I feel helps to eliminate stress, etc.

 

[AdrianB]

So you have three types of lights in your tank aquascaper, I take it you have corals in there. Any pictures?

Sounds like a good idea with the fazed lighting I do a similar thing with room lights on my FW at the moment.

 

[Aquascaper]

So you have three types of lights in your tank aquascaper, I take it you have corals in there. Any pictures?

Sounds like a good idea with the fazed lighting I do a similar thing with room lights on my FW at the moment.

Yep, Actinic T8's, Marine white (10k) T5's and a 400w 14K Halide

No pictures as the tanks being dismantled as we speak

 

[AdrianB]

I found a few pictures that you had previously posted up Aquascaper and they look lovely!

Any reason for the dismantling, moving/giving up marine etc?

 

[Aquascaper]

Downsizing as i'm going into property development and can't keep moving a 160g setup around

Moving eveything to a 40g tank with a sump (haven't decided on the exact size yet)