Questions on Lighting

[BiGBOi]

I know there is always much debate about what type of lighting gets the best results on reef tanks. I want many different opinions to help me make some decisions on some things.
First off, the tank. It is going to be a 55 gallon. I am going to keep mostly softies and lps with a few sps. I am also going to use this tank to propagate corals. I have had VHOs in the past for my 37g and I now use Power compacts on my 20g. IMO I like the spectrum of my 10,000k and Actinic PC a lot better than the spectrum of my URI VHOs (Actinic 03 and Aquasun). I am looking into several things for this 55g. First I considered 1-175w MH with 2x96w PC that give me a watt/gal of 6.7 but halides from what I hear can burn corals if not elevated high enough. I want to put my lights inside a canopy. So then I started thinking about VHOs again and I can buy a retro fit ice cap ballast w/ 4 110w bulbs. But I really don't like the VHO spectrum. These are the two options i have found somewhat realistic. I am considering the second option of VHOs which will give me 8 watts per gallon. The VHO option also seems really appealing due to it's price. I can get them for a very good deal. What is everyones opinion on this? Also with VHOs will I get the same lux as I would with Halides? Should I use a combination of VHO and PC? Thanks for any input.

 

[VkeSu]

I have 4 vho's on a 72gallon. It works great. I have softies, and hard coral up top. Everything grows real well. I agree that I like the mh look and someday I'll do the mh w/2vh on my fresh 55 gallon. Go with what you like and will be happy with. Check out other peoples tanks if possible. That's what I want to do!

 

[StirCrazy]

VHO won't even come close to the out put of MH, if you don't like the look of VHO try a all PC set up. I can tell you that a my LFS the other day I hapened to have my light meter on hand and I measured the surface lumen of a 110 VHO and got 600 lumen, I also measured a 96watt PC smart lamp they had and got a surface reading of 6800 lumen so quite a difference in intensity. I personaly am using two 96 watt bulbs for the light with 3 NO bulbs for actinic in the 65 gal I am sarting to get ready to go.

Steve

 

[HARRISON]

Take a look at my web page and you can see metal halides (10k) with PC (10k-actinic) accents on my 80 gallon. I really like the color.

 

[bmw]

I would dispute those meter readings.
I get about 5000 lux(not lumens) under 4 vho 110s just about anywhere under 6 sq. feet of surface. Its more a "plane" of light,hitting the water surface at 90 degrees, not a point source as is a mh bulb. The further you get from the mh bulb, the less light you are going to get(inverse square law) not to mention the increase angle of incidence with the surface of the water. In addition, the amount of wattage actually used needs to be considered-why compare lights using 25 watts and 100? My icecap ballast is drawing an actual 274 watts. My friends 175 mh on a tar ballast was drawing about 250. Would it be reasonable to compare this 175 hanging alone over a 4ft long tank with the vhos?
Maybe. Something to think about.
b.

 

[31-2c]

I would get a pair of 175 watt MH and use your PC's for Actinic. Just make sure you have a good ventilation fan (or two)

 

[StirCrazy]

BMW multiply footcandles / lumen by 10.745 to get lux.. you will see that I got a reading of 6000 lux ar the surface of a VHO.
Steve

[ December 10, 2001: Message edited by: StirCrazy ]</p>

 

[fishfarmer]

I think the thing about halides burning corals is an old wives tale. I run 1 175 watt MH and two 28 watt PC on my 38 gal. A 55 is a foot longer and a little wider front to back. I have xenia about six inches from the MH bulb. I have various corals thriving under this light, but the far low lit corner opposite the halide can't grow xenia.

 

[Scott D Passe]

Hi All,

As an engineer, I would like to comment on the VHO vs. Compact Fluorescent debate.

Putting a light meter on the surface of a lamp tells you little because of the surface area differences between Compact Fluorescent, VHO, metal halide, etc.

The overall light output of Compact Fluorescent and VHO lamps is only roughly 10% different. (Given the same kind of ballast)

Phosphor is phosphor and for a given wattage and frequency, the output is roughly the same. (regardless of what shape you bend the glass envelope into.)

Some Compact Fluorescent vendors would have you believe otherwise though.

Regards,

Scott

 

[suckair]

I think that stories about halides buring coral may be true to some extent. This is probably due to UVb output damaging them. Some MH lamps especialy German HQI lamps are real bad about UVb and require filtration. I know that many people use Iwasaki lamps with great sucess with no filtration but the Iwasaki lamps do have built in uv filtration in the envelope.

Just some things to consider when selecting a MH lamp for your reef..

Randall

 

[suckair]

Just another note on VHO vs MH/HQI lighting.

PAR ratings show that the only a few lamps have outperformed a Iwasaki 6500 MH lamp in watts/par output.

1. A Phillips T8 lamp that is quite hard to come by in the aquarium trade.
2. Ushio HQI lamps.

Of of these two the HQI wins by a land slide. Cost is a consideration as the HQI lamps to cost more to purchase and the ballasts are also more expensive. It is your electric bill.

You decide. For my setups I run Ushio HQI 250w lamps and IceCap ballsts custom tuned for the lamps to prevent flicker or buzzing. I decided to go with this type of setup on all my tanks instead of 400w Iwasaki lamps to reduce power consumption and operation costs. This may not apply to a 50g setup but is food for thought!

Randall

 

[bmw]

Stircrazy-
Are you getting your units mixed up?
lumen/sq.meter(lux)=.0929 footcandle ; so if we are converting lux to footcandles the 10.745 works pretty well.
But lumen/steradian(candela) = 1 candlepower, not the same at all.
lux is a mesurement of illuminance, right?
lumen is a measurement of total flux of light emitted, equal to the intensity in candelas multiplied by the solid angle in steradians. right?
lumen does not equal footcandle, right?
If all that is correct, then I don't see how we are comming close in measurement.
b.