*~*New DOW -- Reef Lighting*~*

[Scooterman]

Originally posted by Maxx
That is when comparing 500 watts of MH vs 500 watts of VHO's/PC you'r really not going to see much difference purchase cost wise. I'm not an electrical genius so I won't comment on usage costs, (especially since I suspect that MH's are less energy effiecient. But I also suspect thats due to start up energy usage primarily).
Nick

Actually MH lighting is More energy efficient..here is something to chew on. Think about it, put 400W of ANY florescent lighting PC/VHO/T5 , T8 or T12 & you throw in one 400W of MH, which one will produce more PAR per given area? YEP, MH, this is why MH is used for SPS, clams etc, they have more PUNCH per watt of power. Lets not confuse power consumption with light efficiency, if you add an electronic ballast to the equation you will get maximum efficiency per watt Period, there isn't anything better. I do agree wholheartly about the fact that you can thrive a tank without MH, & I also agree that supplementing is the best way to go, start out your lighting with fluorescents them MH & then reverse the process for evening light.

[jimeluiz]

What about bulb/tube life? I have VHOs. I'm guessing that they will slowly fade... but then I will have a hard time noticing the difference while our critters slowly suffer. What is the 'standard' switch-out period? One year? Shorter, longer? Are there subtle, predictable changes in appearance that will alert me to the need to change out tubes?

Also, regarding reflectors. The tubes have internal reflectors built in to the top of the tube. My guess is they help lots, but adding a shiny aluminum reflector on the inside top of my hood would boost matters further. Any guesstimates on the percent increase? Sorry to go fishing for fractions of advantages, but perhaps I would be surprised by the increase. It may get me off my duff and to Home Depot. I do notice that the edges of our tank are considerably 'darker' than the center. A reflector would help.

Thanks in advance.

[Craig Manoukian]

Scooterman,

Can you provide a good working definition/description of PAR value? TIA

[strat]

great topic, ive gotta run to work but.... my uncle works for an electrical wholesaler, he manages the place, and he says that he can get me 250 watt MH bulbs for 14 bux CDN.... i almost freaked. and all the ballasts etc will be similarly cheap. im wondering if these lights will work even tho they arent made by a 'reefing' company, as long as they are 10-20ooo K?? any ideas, i have to look into it more, and see if i can get some online info about the products he has access too. but if anyone already knows the answer lemme know... (it kinda feels like cheating) LOL.. BTW xm bulbs etc here online cost about 110 bux.. yikes

thanks in advance

strat

[Craig Manoukian]

Strat,

Off the top of my head, make sure the fixtures are for the highly corrosive salt water environment. Rubber seals for protection are part of all marine set ups. great price and to my knowledge 250 watts of 10,000k MH lighting is just that. Some bulbs will produce more white, blue, or yelloew looking light depending on the manufacturer.

[Woodstock]

Below is a definition of PAR that came from this link: http://www.coralreefecosystems.com/l...htm#Blue%20PAR



"Photosynthetically Active Radiation (PAR): A measure of visible light intensity (400-700 nm) obtained by using a quantum meter. PAR is simply a count of photons falling upon a surface in a given time and is reported as “micro Mols per square meter per second” (µMols·m2·sec). Quantum meters report all wavelengths between 400 and 700 nanometers. However, they report only light intensity and do not account for spectral quality. Generally, maximum solar PAR values are 2,000 – 2,100 µMols·m2·sec. PAR is something of an outlaw in the scientific community; it is not recognized as a standard unit, however most major works in the field (notably Kirk (1983), among others) state compensation and saturation points (see below) in PAR units. (Since PAR is a relative new-comer to science, it has not been recognized by CIE (Commission Internationale de L’Eclairage) or the International System of Units (SI) – both had already adopted standards for measuring light intensity. Lack of recognition by either of these committees should not undermine the importance of PAR measurements. Incidentally, divide µMols·m2·sec (of sunlight) by 4.6 to convert to watts per square meter per second (which is a SI-recognized unit.) A quantum meter is better suited for reporting light intensity than lux meters. Lux meters are photometric in their response, that is, they “see” light as the human eye does and have a maximum sensitivity to green wavelengths. The human eye is not especially sensitive to those wavelengths known to promote photosynthesis (violet, blue and red). Generally, noontime lux measurements made on cloudless days in the tropics range from 100,000 – 120,000 lux."

[Scooterman]

WOW good questions.

First: What about bulb/tube life?

Boomer posted that any fluorescent will need replacing at 6 months (I will have to look that up, also the PAR question), you can't see the drop off but tested it does, even though the manufactuer says it will last a year or more. I have yet to replace them so often but the last set is fairly new so I will be looking for signs of unexplainable algae blooms etc.
My VHO lights also have built in reflectors, as I installed a reflector when I first set it all up, I have nothing to tell if it makes a big difference, I just feel the I do get more reflection & benefit from not having bare wood next or close to any lighting, the metal reflector acts as a barrier & heatsink.

BRB

[Scooterman]

Thanks woodstock, if any of that listed need simplified post away, I'll see if I can avoid confusing myself LOL!~

[JB NY]

Let see what I can answer.

What is PAR?

Photosynthetically Available Radiation (PAR). PAR is the available light between 400-700nm (nanometers). This spectrum is the light spectrum that we, as humans, can see. It is also the area in which photosynthesis occurs in plants. There is some debate as to wether the whole spectrum, 400nm-700nm, applies to corals, but for now it is thought of as the range in which photosynthesis for corals can occur. PAR is measured as Photosynthetic Photon Flux Density (PPFD). PPFD measures the number of photon that show up on a given surface in a period of time. It is measured in microEinstien/m2/s.

PAR and PPFD, can and are, used interchangeably.

So basically the PAR value just represents how much light is available to be used by the coral.

On reflectors.

You can build your own, but will get much better results buying one. To give an example of what a good reflector can do. Look at the DE reflectors as opposed to SE reflectors. DE reflectors were, for the most part, designed for aquarium use. Most SE reflector, were just ported over from the horticulture industry and are not nearly as good. What this means is that lamps in a DE reflector generally put out significantly more usable light than SE lamps in reflectors. Even thought the SE lamp itself puts out more PAR the a DE lamp. So basically the reflector makes a huge difference in getting the most light for your money.

Swapping bulbs.

Most people recommend swapping out MH lamps every 12 months. Radium lamps shift much earlier and should be changed every 6-8 months. I change my VHO at 12 months as well.

HTH

-Joe

[Craig Manoukian]

Thanks Joe and I am still only slightly confused on PAR!

[Scooterman]

Photosynthetically:
synthesis of chemical compounds with the aid of radiant energy and especially light; especially : formation of carbohydrates from carbon dioxide and a source of hydrogen (as water) in the chlorophyll-containing tissues of plants exposed to light; PAR (Photosynthetically Available Radiation), layman's terms is the useful amount of converted light into useful food source to the corals. MH lighting produces more of this useful light than any of the fluorescents, thus another reason they can grow sps, clams etc, fluorescents would take 1000 lamps to 1MH lamp to get that same amount of PAR rating. That is extreme examples but gets the point through, and even if you had that much more fluorescents, I still don't think they will penetrate as deeply into water as a MH of any wattage, in extreme terms.

Now please don't mis quote me on those extream examples, that is just used to get the point across, not actual values, which would need to be charted.

[JB NY]

Maybe this will help too.

Just think of PAR as just a number. The higher the number the more light is available for photosynthesis.

-Joe

[Craig Manoukian]

Thanks Joe and Scott A. I can get my arms around those concepts and it makes total sense!

[jks1]

lets throw a wrench in here, why is a 250W 10K bulb considered "more intense" than a 250W 20K bulb? Is this a PAR difference between the bulb, or just a color thing?

[Woodstock]

PER MOJO REEF in a different thread/forum:

THANKS MIKE!!!

For growth zoox have chlorophyll’s pigment they have strong light absorbing capabilities within the violet/blue area of the light spectrum and can also absorb a significant amount of red light. They also have carotenoid peridinin pigment which absorbs blue light along with some violet and some green. Satisfy this and the coral will grow.

Now for coloring :
>Pocilloporin primarily absorbs green/yellow (550-600 nm) light along with some upper UV-A . it emmits a orange/red
>highly fluorescent pocilloporins primarily absorbs light from 310 to 380 nm (UV-B and UV-A) and then fluoresces this as light from 400 to 470 nm (violet/blue).
>highly fluorescent pocilloporin primarily absorbs light from 380 to 470 nm (UV-A, violet and blue) and fluoresces light from 475 to 520 nm (blue and green).
>third type of highly fluorescent pocilloporin primarily absorbs light from 430 to 490 nm (violet and blue) and fluoresces light from 490 to 540 nm (green/yellow).
>Yellow fluorescing pocilloporin primarily absorbs light from 440 to 500 nm (blue) and fluoresces light from 520 to 620 nm (green, yellow and orange).
>Red/Orange Fluorescing pocilloporin that primarily absorbs light from 500 to 540 nm (green) and fluoresces light with wavelengths that are primarily orange to red.

Ok so now we know what color we put in and what color will results, so lets translate that to bulbs.
here is a 20000K radium wave plot 400 watt.


So looking at that, then translating into what we know. We could assume to get alot of of dark green, blues, some yellows and sme deep reds. But for growth it doesnt have alot of red or green or violet so not alot.



so looking at this we see good violet which translates to violet and blues, and strong 500 to 600 so good oranges, reds,greens
ok so heres some more charts you do the math, lol
here are a bunch of 400 watters



and some 250 watt de's