Reef lighting not so basic

[coopersx]

I am posting these 2 questions here because I am certain anyone with a reef tank also has some sort of high output lighting. General rule of thunb is 3-5 watts per gallon for medium light loving corals. Ignoring the fact that it really is not the wattage per gallon but the distance from the light scource where the coral is placed that matters most.
1: Say I place a coral 10" from the light scource. Is 130 wattts of full spectrum flourecsecnt lighting just as effecient to that coral as 130 watts from a full spectrum power compact bulb...everthing else being equal. If not then shouldn't one be able to get by on less wattage per gallon with the power compact lights?
2: Some corals, algaes, etc. need some blue actinic lighting to flourish ( I think?). Should one combine the wattage from the blue actinic lighting with the full spectrum lighting for determinig the *total wattage* when using the 3-5 watts per gallon rule.
Example: Say I am using power compact flourescent lighting. The unit has a 65 watt 10,000K full spectrum daylight bulb and 65 watt 7?? nm blue actinic bulb. Does this mean my tank has 130 watts of lighting per gallon when using the 3-5 watts per gallon rule. Or do I only have 65 watts per gallon....since the blue actinic bulb does not count. I have read and been told conflicting info about this.
Thanks, Wayne

 

[reefnut]

1. Power Compacts are Fluorescents. The 3-5 watt rule only works if you are using a high output fluorescent (HO, VHO, PC). This rule does not apply to normal output fluorescents.
2. Add them together, the tank in your example would have 130w of PCs.

 

[bang guy]

1 - Watts per gallon is a general guideline, not a rule. Once you get an idea of your livestock and a rough idea of lighting requirements in terms of watts you need to press on to see what fits your system.
2 - I know of no animals that require blue light to flourish. All light is useful, blue light is slightly more useful for some photosynthetic animals but generally Actinic bulbs put out less light energy so it's pretty much a wash. Just count the watts and light the tank in a way that appeals to your eyes.
The notable exception are the Power Compact bulbs that use blue glass to achieve the "Actinic" look. They should not be used in counting watts. You're better off not using them and getting a bulb that uses phosphors to obtain the blue look.

 

[coopersx]

Thanks for the replies. Hi Shark. Power compacts are fairly new and I am almost certain that full spectrum flourescent bulbs ( not full spectrum flourescent power compacts) were being used at the time estimates were being made as to what lighting requirements were necessary for certain corals, etc. to thrive. The power compacts are most definelty shorter tubes for the wattage supplied. But some speak of the them as being 2-3 times more effecient than compariable wattage full spectrum flourescent bulbs. Maybe I am confused but I thought these do exist and are the same full spectrum flourescent bulbs that were being used at the time that estimates were being determined at 3-5 watts per gallon...not todays power compact flourescents.
So if the power compacts really are more effeicient then comparable full spectrum flourescent daylight bulbs (same wattage) then wouldn't less wattage per gallon be neeeded with the power compacts. This is what I am asking and maybe the correct answer is they are both the same but it takes many more full spectrum flourescents than the power compacts to reach the appropiate wattage. I really don't know but some have said that less wattage per gallon is needed when using metal halide or power compacts because of the effeciency difference which I am asking.
Sincerely, Wayne

 

[reefnut]

I can say it again but my answer would be the same.
The "full spectrum fluorescent bulbs" as you are referring to only tells the spectrum of the bulb... it says nothing for the type of fluorescent bulb it is.

 

[reefnut]

But some speak of the them as being 2-3 times more efficient than comparable wattage full spectrum fluorescent bulbs.
Ok, by "full spectrum fluorescent bulbs" you mean the normal output (NO) flourescents... PC and VHOs and HOs produce more light than NO Fluorescents. Again, the 3 watts per-gallon guideline does not apply to these bulbs. NO bulbs should only be used when corals are not present or as a cosmetic light.

 

[coopersx]

Hi Shark and thanks for restating this. Sorry
One person had stated that you could get by with less wattage when using high output lighting vs N.O. florescents. I kind of doubted this and was wishfull thinking. It really would be nice...I mean cheaper <G>... if 130 watts of full spectrum power compacts was equivalent to 260 watts or higher (per gallon) of the necessary full spectrum lighting that is required by many corals and the like. Thanks for clarifying this.
Sincerely, Wayne

 

[reefnut]

This is why the watt per-gallon rule is no role but more of a "go by" as Guy mentioned. It's misleading and often causes more confusion than anything.

 

[bang guy]

Originally Posted by coopersx
But some speak of the them as being 2-3 times more effecient than compariable wattage full spectrum flourescent bulbs.
Anyone claiming this has not done the research. The Normal output flourescent bulbs are actually slightly more efficient than PC, VHO and even MH in some cases. What they lack is lighting intensity, ie. the ability to penetrate coral polyps and give energy to the photosynthetic Dinoflaggelate symbiots that give corals extra energy.

 

[bang guy]

Originally Posted by coopersx
One person had stated that you could get by with less wattage when using high output lighting vs N.O. florescents. I kind of doubted this and was wishfull thinking.
This is true to some degree. This is why research is important and you need multiple opinions and explainations. As stated above, 400 watts of NO flourescent lighting is less effective than a pair of 150 watt HQI. This has to do with light intensity, the ability for light to penetrate.

 

[coopersx]

Hi Shark and no disrespect. By my problem was not so much lack of reserch as opposed to my lack of understanding that research. It was not untill your post that I realized that NO flourescent lighting that you mentioned should not be taken literaly. In other posts when someone mentioned NO flourescent lighting I thought they meant no lighting at all <G> I now know this means Normal Output which some also term Regular Full Spectrum. Before Vita light went out of buisness those bulbs had been in use for years. It appears many reef aquarists have had good success using these Normal output full spectrum flourescents but they were long and many bulbs were required. I do not know if many people use this type of bulb today over there reef setups. I now understand these do not have the same penetrating power as the selection offered as High Output. But I do now know that the 3-5 watts per gallon rule/claim does not apply to these Normal Output Full Spectrum bulbs ( I do understand that watts per gallon is not an literal arbitrary # that applies to everything, but I Know of no other way of mentioning it in a post) Thanks again. Sincerely, Wayne

 

[bang guy]

Originally Posted by coopersx
Hi Shark and no disrespect.
Hey Wayne, none taken at all. It sounds to me, from your post, that you're beginning to grasp the big picture. Congrats. Also keep in mind that it's good to pursue other opinions as well even if you don't heed the advice. The more knowledge you acquire the better your decisions will be.