[ben]

how important is actinic lighting to our corals, and what does it actually do for them?

why are narva tubes better?

cheers
ben

[Social D]

Ive read they do nothing beneficial to corals themselves, Ive not used them in 2 years and dont consider them a must have but will get some one day for a bit of blue

[Simon Garratt]

Ooops, for fear of upsetting anybody and not wanting to put anybody down (well, exept those who deserve it )...

Believe it or not, this is one of the biggest myths in reefkeeping today, so much so, that ive heard and seen proffesional coral farmers etc state that actinics do nothing for corals on several occasions (and these guys really should know better...or at least they should understand the light feild and photosynthesis).


Fact: Most Actinic tubes kick out a concentrated light feild between about 380nm and 500nm.

At the lower end there is a small amount of whats termed black light or UV A which causes florescence in some corals, but the bulk of the output is around the 400-500nm range...Now strangely enough (and yes i am being sarcastic) , a corals photosynthetic peak in absorption just happens to be at around 420-450nm becouse over millions of years, zooxanthallae have become adapted to using light (predominantly) of these wavelengths becouse they travel through water far better than light from the red end of the spectrum (650nm+)....

There are in fact two peaks in photo synthetic activity in marine algae, one at 420nm (blue end) which makes up around 70% of activity, and another at 650nm (red end) which makes up around 25% of activity, with a small amount of absorption right across the range between the two oposite ends (around 5%) which is not fully understood as to what roll it pays...(those figures are purely representative, not fixed)

But anyway.. getting back to the subject...


Whilst admitedly Actinics dont offer 'full' spectral and photosynthetic coverage, they do give the most 'dedicated' output of any just about any commonly availabl light source, smack bang in the range that corals are 'most' adapted to absorbing for photosynthisis...

The offshoot of this and one of the main reasons that certain keepers like them, is that with the small amount of UVA they kick out, they do induce enhanced pigmentation in some corals, especially green and blues.


So, if anyone ever tells you that Actinic tubes serve no purpose... just point out one fact...


That pound for pound, a 54w actinic tube with its dedicated spectral output, probably puts out more photosynthetically usable light than some far more powerfull light sources that spread thier power across a far wider range of the spectrum, which includes frequancies not even applicable to photosynthisis and serve no other role than to make a coral visible to the human eye, and 'look' pretty.


The quickest of searches gave me this....ignore the sales patter....look at the wavelengths quoted and the spectral chart..Arcadia actinic tubes


In all honesty, i cant really blame 'hobbyists' if they believe the wrong thing, especially when its banded about by so called proffesionals so often.


regards

Si.

[SlyOne]

Reason i use actinic lighting is to view the corals for a longer amount of time. I have also noticed some of my fish get a bit more active and come out the rockwork more with just the actinic lighting, my mandarin especially likes to come into view under moonlight effect. I have used many brands of blue for the moonlight effect ( including several brands of the blue T5 tubes and the fabled moonlight led's in all there forms from ebay ),but since changing to the Narva blue all i can say is WOW, my corals glow like you would not believe,and i have also read that narva blue tubes work in the twenty thousand k spectrum which is benificial to some corals ( can't remember were i read it,but upon remembering i will post the link ) At one point i had the T5 narva blues and my halides on,but changed it to t5's on at different times to halide as my water was getting far to warm for my liking,but it did punch the colours alot more then just the halides themselves, if i get a chiller i would probably put them back on again during the day and not just in the morning before halides come on and at night after halides go out.

[chriss]

i'm a firm believer in atinics after reading many writeups alluding to what Si has said above. I've been running Narva blues since christmas and believe they look fantastic, I don't know how good they are spectrally, but corals AND fish look great with them. I run 1000W of 10K reeflux, don't like the dimness of the 14K's and think they are too blue, but even a single 58W narva tube makes a visible difference against all that halide power. I have a second one in place but think it would be too blue for my liking if I was to use it.

The other great think about these tubes is the price, cheaper than most marine whites!

Chris

[ben]

to carry on with this a little bit. because the actinics help with photosynthesis, does this mean it helps with growth?

[karnivor]

Something else I picked up whilst surfing.

When curing Live rock, use only actinic lighting as it will feed any corals on the rock, but will have a limited effect on Algaes as they prefer longer wavelengths.

If you use the same thinking in an established reef, could this also act as a means of controlling Algae.

[Simon Garratt]

Just as a continuation on this, and to confirm what i was saying earlyer. i ran some test last night using an apogee PAR meter with remote sensor.

taking readings from a set of twin 54w t5 narva blues in a direct line underneith. (all other light sources were turned off)

6" from the tubes (at the waters surface).... 295ppf

6" under the surface.....121ppf

12" under the surface....81ppf

24" (bottom of the tank)...75ppf


Par value at 24" depth... strait under the center of a 400w 10K BLV........128ppf


Remembering what i was saying earlyer about the more dedicated spectral control of the Narva compared to a wide spectrum light source like the Halide which has peaks at 'both' ends of the photosynthetic range, and the waters ability to filter out Par values from the red end of the spectrum as you go deeper. What this hints at is that watt for watt, a pair of 54w t5 narva blues kick out nearly as much PAR in the blue 400-450nm range as a 400w 10k lamp.

So as i said, if anyone ever tells you that T5's dont do anything for corals, they are talking rubbish.

Regards

Si.

[Tony B]

Very interesting thread, nice results from the par meter - not what I expected, thanks

Regards,

Tony

[Social D]

Interesting, I dont use Narva Blues i have 2 x arcadia 54w Blue Moons which do a good job, But i wonder how they compare with Narvas, In terms of Par value

[Simon Garratt]

Not sure realy to be honest as moon tubes are more a cool white peaking at around 450-500nm iirc rather than a true actinic blue which peaks at around the 400-450nm point. my gut feeling would be that they would be alot lower in par even if they offer the same intensity. but you would need to see the spectral chart to have any real idea.

regards

Si

[matt h]

interesting read,i was thinking of changing to 14k bulbs instead of the 10k's i run at mo with 300 odd watts of actinic[aquamedic]to save a bit on lecky,having read through im sticking with what ive got...

[Simon Garratt]

Well Matt.

What this basically tells us, is that if you want to add 'more' light over a tank, without going overboard on electricity consumption and factoring in the types of corals you are keeping (deep or shallow water Sp) then in some situations you are probably better off adding actinics, than say another halide.

I say that in a reserved manner, becouse whats crucial here is what types of corals you are keeping, and the type of light they need. PAR is a pretty crap measure to be honest becouse it doesnt tell you what the 'mix' of light is within the photosynthetic ranges of 420nm and 650nm. All it does is give you a 'total' for want of a better word.

Corals that come from shallow water like A.Humilus are attuned to a more 50/50 mix of these two peaks ie they need some of that red light, whereas a deeper water sp like A.efflorescens are better at using the 420 peak becouse most of the 650 peak has been filterd out by the time it gets to them.

So taking A.Efflorescens as an example. If you wanted to give it more light, you'd probably be better off chucking a 54W actinic over it which will convert most of its input energy into usable light at the 420nm end, rather than say a 10K lamp which will waste energy, putting out a proportion of light thats of no or little use to the coral in question.

Swap it round the other way and have A.Humilus there, and the opposite would probably apply, You'd probably find that although it will still use the 420nm range, youd be starving it of light in the 650nm range and it might struggle to meet its energy demands.

regards

Si.

[matt h]

si, at mo i run 4x400 watts split into pairs and then ive 3x54watt and 2x 80 actinics so three different timers..
they run actinic's. on at 11am off at 12pm these then come back on at 8pm till 10.30...
my halides come on at 11.30 first pair [1 and 3]and then 2 and 4 [these over lap by 5 mins]each pair run for same amount of time on there own ,at 7pm they all come on together and out at 9pm..h t witing
so would i be better extending my actinics time?
the growth of most corals in the tank have been great imo but i do have a few which struggle,ive been thinking of changing to 3 halides,any opion on wether 4xlumenarc large reflectors with coralvue 10k bulbs is to much for a 9ft tank

[ben]

si, what was the par reading under the halide, at the surface of the water?

[Simon Garratt]

702ppf ben...smack bang dead centre, 8" from the lamp, taken at the weater surface..

That is a 9+ month old lamp though, and to be honest, my mini luminarcs need a good clean/polish as they are loosing id say a good 20% reflectivity..


regards

Si.

PS, the tubes are about 6 months old iirc

[ben]

what amount of light , par, ect is lost in the air between the reflector and the water surface?

also si, sorry i may have missed it, but what does "ppf" stand for?

[Simon Garratt]

Hi ben. sorry i missed that you'd replied again.

You dont actually 'loose' PAR through air as it were, what you get is a wider spread of photons as you travel farther away from the point source. (imaging standing under a shower head, the closer you are to the head, the more water droplets hit you, as you move further away, the spray gets wider and the number of water droplets hitting you gets less as some pass by on either side) The same happens with the light sensor, the further away you are from the lamps centre, the wider the photons are dispersed and the less photons hit the sensor.

The same happens under water as well. Photon despertion is one reason for lowerd PAR at greater depth, then there is refraction and absorbtion by turbidity and chemistry.

PPF stands for Photosynthetic Photon flux density, sometimes written as PPFD.....A PPFD of '1' corresponds to 6.022 × 10(to the power of) 17 photons falling on a 1 meter square area per second..

When we say PAR we are in fact talking the same thing near enough...PAR= Photosyntheticaly available radiation, PPFD/PPF is a measure of the total density of photons in all those wavelengths that make up the Photosynthetic range hiting the sensor at a given time..

The important thing to remember though, is that PPFD/PAR measurements are only of use if you understand the conditions they were conducted under.

When someone says they have a PPF of X it doesnt mean anything to 'you' unless you are running the same kit under exactly the same conditions. with lamp type/colour and reflector being the largest factors.

Here i have compared two light sources over the same area and the same body of water with the same meter. one using a mini luminarc with an aged lamp, the other using a strip light (non point source light) so my comparison is applicable only in this instance and with these two sources under these conditions.

There is no doubt in my mind that somene using differing kit under differing water conditions would get completely different readings, although the 'trend or ratio' should be fairly similar...that is all i'm trying to show here. ie that actinics do indeed give out 'usefull' radiation, and that they are 'watt for watt' more than capable when it comes to taking on much more powerfull 'full' spectrum light sources with regards to light emited in the 420nm range.

regards

Si

[Roshan]

Simon / All

Very interesting thread and very helpful. I'm about to include soem additional lighting and just wanted to clarify the colour of the Narva tubes that has been mentioned.

Is the Narva tube alike to a true actinic 03 tube such as the d&d actinic, or is it more alike to the d&d actinc plus (blue tube) / ATI Blue+

I'm lokking for an actinic colour output but just wanted to clarify what the output of the Narva will be like.

Thanks
Roshan

[Simon Garratt]

Hi Roshan.

The narva has a solid blue colouration to the eye unlike some Actinics that are either purply blue, pinky blue or pale blue.

Personnaly, i prefere the Narvas or aquascience Actinic (which are basically the same) becouse as they age, they dont drift out of the blue so quickly....Ive had some makes that have drifted to visible Pink in a matter of 3 months in the past, whereas narvas have stayed blue for up to 2 years with just a visible loss of intensity and slight drift from deep blue to pale blue.


Regards

Si.