VHO, PC, and MH efficiency compared

[dmh]

Okay, I did a little research to try to clear up my (and others) confusion regarding this whole 'watts per gallon' debate. Obviously saying the 'watts per gallon' rating is the same for VHOs, PCs, and MHs cannot be true do to efficiency discrepencies. Also, the 'gallon' is really meaningless, the depth is what's important. If you have a coral under 4 feet of water, it will require a much brighter (at the source) light than one at 12 inches, but we all know that. A tall, thin tank will require higher intensity lighting than a large shallow tank, even if they are the same volume.
Anyway, I was able to determine a 'lumens per watt' rating for each type of lighting system, and thereby able to include efficiency in determining the sufficiant amount of light.
Let's assume that the 4-6 watt/gal standard that was always used for VHOs is correct, and let's say 5 watts is what we are after and we have a 55 gal tank, so we need 275 watts of VHO lighting. This 275 watts, (this all assumes 8-10K daylight, you get far less lumens from actinic) will yield 14850 lumens. (*note, this is far more than the 10K lumens/square meter that has been cited other places, but we will assume the 14850 is correct.)
In order to achieve the same lighting with power compacts, you need only 175 total watts, and with metal halides you need only 165 watts.
NO flourescent produces 65 lumens/watt
VHO flourescent produces 54 lumens/watt (some energy is dissipated as heat)
PC produce 85 lumens/watt
MH produce 90 lumens/watt
There is some variance between brands, but generally these rating seems to hold true.
Does anyone know how much light is TOO much for corals? Anyone ever 'wilted' one?

 

[flydan]

Hmmm.... Very interesting. But not funny. Ha!
Are you saying that NO put out more lumens than VHO? I'm guessing that VHO has more watts per bulb, thus puts out more lumens so you get more bang for the buck. Do I have that right?
Anyway, I've heard it's almost impossible to put too much light on your tank. That's why people generally start by placing their corals lower in the water and moving them up until they (the coral, not YOU!) are happy. If you have an established tank with corals ect all over and then crank the lighting up you will get some bad reactions. HTH, thanks for your research.
Take care,
Dan'l

 

[beth]

One factor that very much throws out the "watt per gal" measurement is also the type of creatures and corals that you plan on using in your tank.
I think the bottom line is that the individual hobbyist needs to decide what type of reef system he/she wants to setup and gear the lighting choices based on that reef system's requirment.

 

[dmh]

FlyDan - Not saying NO puts out more lumens than VHO, in fact it's not even close. This is because NO requires fewer watts. It is more effeciant (barely) on a lumen/watt basis than VHO, but VHO can run 110 watts, whereas NO can't handle anywhere near that. Depending on the voltages, it may take 5 NOs to equal 1 VHO.
I guess the crux of the post is just to point out that if you go with PCs or MHs, you don't need as many watts as the watt/gal formula might tell you.

 

[dburr]

Nice research DMH!! You did answer alot of my questions!! I never did like the watt method. Thats I think is for the metermaid that tells me how many watts I used for the month and how much to pay. Congrats
Dburr

 

[stalyun95]

so how much light or lumens or no bulbs to sufficently lght my 90 gallon hard and soft coral reef tank.......bottom line no more brain work just tell me how many no bulbs please!!!!!!!!!!!!!!

 

[burnnspy]

That info in my opinion is too convoluted and useless to novice reef keepers and just adds more confusion to the mix.
The corals you choose and tank depth, dictate the kind(K value) and intensity of the lighting needed.
Stalyun95 - You can't get enough NO(normal output) lights in a normal size aquarium to maintain the 'normal' coral choices.
BurnNSpy

 

[tnreef]

BurnNSpy,
Someone has taken the time and effort to research the lumen output of bulbs vs Wattage and all you can do is shoot them down. This I disagree with. We all agree lumen output is the way to go in deciding what is needed for the livestock. You have a very negative attitude on this board and your are a Moderator. As you are famous for telling people to research what they want to keep and decide lighting from there. How do you know the light requirements of each coral? Watts are out Lumens are the only way to go....
The Marine-Biologists and researchers cannot even agree on the best lighting for tanks. How can you know more than them????
I have watched you put people down for as long as I have been on the board and I think you need to lighten up.
Go ahead flame me kick me off the BB do as you wish. This is my opinion on the way you respond to good input to this board.
This board has been setup by SWF for hobbyists to share info.
DMH Thank you for sharing some good research.
IMO Darryl

 

[coralbeauty]

I have to agree with TNreef, I found the research very interesting! I also think light is only one factor. Placement, water movement and quality are also very important factors.
Thanks for spending the time and doing the work for us! It is always great to look at something from a different perspective.
Connie

 

[burnnspy]

If you read my reply word for word you would see I only mention confusing novice reef keepers. Most people who ask lighting questions are usually novices. It is my opinion that adding another factor to consider when purchasing lighting will only make the decision harded then it already is.
I don't really care what biologist think, actions speak louder than words. Look at what the coral farmers are doing and look at the lights they use. Since they are obviously doing it right, then that is what I model my lighting advice from.
Having a different point of view or attitude doesnt make my advice any less worthy of considering. I wasn't aware that being a moderator required me to be a Walmart greeter also. I try to be factual not emotional.
BurnNSpy

 

[dmh]

BnS, just want to let you know that my intent in posting the info was not to confuse anyone. I am a novice reef-keeper myself, and found it odd that people talk watts/gal regardless of the type of lighting being discussed, and even more frustrating that it is so hard to find lumen ratings for standard flourescent lights. When you are trying to decide which way to go, I think it's nice to have all the facts and be able to make the decision that's best for you. Also, remember that just because someone is a novice reef keeper it doesn't indicate that they have an inability to understand complex logic. I've met some people with outstanding tanks and years of experience who would have had their mind blown by my post, and others who probably couldn't keep a goldfish alive for a week who would consider what I posted as pretty simplistic. If the information is difficult to understnad, then don't consider it in your decision. I just thought it would be helpful for those who were searching for that info if the post was made so they could do a search and find it at their convenience.
Hope it was useful to someone.

 

[nm reef]

DMH....excellent post.....great info.........I too searched and found basically the same type info before I started the lighting quest..........My game plan was to start with 2x65 watt 50/50 pc's.......designed a custom canopy....added 2x65 watt 10k pc's a month later....then just recently added the final lights....2x110 watt VHO uri actinic blue........lighting is done and all is well...........and for me and my 55 reef this lighting is fine.........every thing I've added is doing gr8.......now IF I was to set-up a 100+ reef.....maybe then I'd seriously consider MH....or MH/vho combo....or even MH/PC combo.....heck maybe even tons of vho..........then again IF I was going to maintain propagation tanks MH would be a serious consideration......
But I have a 55 reef that has a few fish.....assorted crabs/snails.......leathersx2.....polyps x 4....mushroomsx5.......bubble coral....green star polyps.....closed brain......open brain.........hammer.....and will eventually add additional LPS as well as SPS corals ...............and guess what.....all this the same as countless others.......without MH....go figure......!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
lumens....intensity.........type of set-up and desired friends in the reef are considerations to ponder.....and in my modest opinion....there are most certainly options available other than MH

 

[misty]

Thanks for the research, DMH!
I have been doing my lighting research for about 2 weeks now (and have been driving myself nuts with all of the factors to consider!).
Since I live in Dallas and my tank runs 81 w/ just a 40w NO right now (plus powerheads, etc.), I didn't want to start with MH (it's over 100 degrees outside everyday for the next month or so!). But I did want to get quality light. So I've finally decided to start with 220w from PCs and my 40w NO. I'll upgrade as needed, and have room for a retro MH or VHO if I decide that I want one.
I'm not even going to buy a fish until we get back from vacation in September, so I'll have very happy hermits and algae until then...

 

[flydan]

Hey,
IMHO I think the sharks just play, "good cop, bad cop". BnS is the bad cop. lol Anyway, I think the advice here is good. Some of it smacks you between the eyes and some is sugar coated. Anyway, I still appreciate it when someone goes to that kind of effort. What I do with the information is my business, good or bad. We hear constantly about people being given a lot of real sound advice and then they chose to do something totally different. Their aquarium, their choice.
I just want all of you, sharks to newbies, to know that I appreciate your contributions to this board.
Take care,
Dan'l

 

[corky]

DMH- thumbs up as others have stated on all your efforts and research. Each bit of information can help the next person take yet another step forward.

 

[ironreef]

I agree it is confusing. lumens on a 4' pc and on a halide still aren't gonna have the same intesity.. When comparing pc and halides some may think they are equal. Having pc,vho and halides and others who have both or all most will agree halides will produce more intesity deeper but not as wide. 500w of halides vs 500w of pc halides will produce better growth.But I guess that's not the point.Lumens aren't equal either depends on where you measure in your tank. 6" down 12" down ect.. I just recommend vho/pc as min lighting depending on what you keep. Don't skimp on the lighting or pumps. Filtration can be done many ways and I wouldn't skimp on that either. Buying it twice cost more. But comparing lumens on halides with halides aren't equal either. You can look at Sanjay's site he has bulbs broke down in lumens,par. Difference with new and old. Difference between 10k 6.5k 20k difference bettween different brands ect. But there really isn't to much on vho/pc.. there is but not much.
[ July 30, 2001: Message edited by: Ironreef ]