CAn some one please explain Diff between CF and MH

[nikesmashing]

Can some one please explain Diff between CF and MH lights.
if a light is 130 watts with a 10k bulb what makes a MH better than a CF?

[drw94]

The wattage and kelvin may be the same but the intensiy on a MH bulb is so much brighter. Try looking at a normal light bulb and then at a cars headlight. They look totally different. But the thing is they both run around 55 watts. Hope this makes sense, maybe someone else can explain it better!

[rottielover]

A MH light works like your typical light bulb, it has a filiment that "burns" to produce the light. CF is basically a floressant light, bent in 1/2 with the connectors at one end instead of both ends. Floressant lights work by charging the gas contained inside, these charged atoms produce UV radiation (light) the inside of the glass tubes are coated with phospors that glow when hit by UV, giving off the light. (don't worry no UV get's out as far as my reading has taught me)

Let's say for example you have a 60" tank like mine. If you take a CF fixture 60" long it has 4 65watt bulbs in it, (I use two strips for a total of 8 bulbs and 520 watts). Now if you look at the MH fixture in this size, it has 3 MH bulbs and two VHO floressants in it, that give a total of 560 watts... When I purchased my lights the two CF strips were $200 LESS than buying the MH fixture, at ALMOST the same wattage. MH bulbs are very intense, but very local, you need 1 bulb for every 2 square foot of tank (or so), CF light bulbs are longer and in the right fixture have a reflector running the lenght of the fixture, and "spread out the light" IMO more.

Anyway, in my case the CF fixtures made more sense to me (also check out several articals saying that CF bulbs rated for xx watt's are actually brighter than you might think), cost wise, space wise, and heat wise. CF's do produce heat, but not as localized like MH (your not going to get burned skin with CF) and if you get fixtures like I did with nice big fans, then you won't heat your tank up as much as with MH and require a chiller.

Basically, I bumped into a gal I work with that has a reef tank. She told me that she hated dealing with her MH lights, and would go with CF lights had she had it to do all over again. I took that advice to heart, but I still did my research on lighting.


Send me a PM sometime, maybe you can come over and see my tank, see what you think.

[rottielover]

Just in case your wondering what I'm talking about, here is a link to the light fixtures I purchased.

http://www.current-usa.com/products/orbit.html

I sent them an email back in Nov, asking if they were going to post some PAR data, they told me in the reply that they were working on compiling it, and I should look for it 1Q 05 (by march).

[nikesmashing]

I completely understand. what i don't get is if the 2 lights are in the same lighting spectrum 10K and both the same watts. then what is the diff?

I could understand if CF were only 6,700 and the MH were 10K, or if the CF's were 10K and the MH are 20K. because i uderstand it all comes too the light spectrum. Bcause if i need to by a HM I wana know why. and LFS can not give me a straight answer, and everthing i read says I need MH. but the people at the plant store say as long as the spectrum is the same its the same. But they could be full of it...HELP!!!!!!!!!!!!!

[rottielover]

Originally Posted by nikesmashing

I completely understand. what i don't get is if the 2 lights are in the same lighting spectrum 10K and both the same watts. then what is the diff?

If the lights are the same spectrum,and same watt's you can still have an intensity differance, this is mesured by PAR rating (photosynthetic avalible radiation). However, I don't belive that there would be a differance (ie hypothetically if you had a 96watt MH bulb @ 10K and a 96watt CF @ 10K, I don't see what the differance would be, other than the heat.

Originally Posted by nikesmashing

I could understand if CF were only 6,700 and the MH were 10K, or if the CF's were 10K and the MH are 20K. because i uderstand it all comes too the light spectrum. Bcause if i need to by a HM I wana know why. and LFS can not give me a straight answer, and everthing i read says I need MH. but the people at the plant store say as long as the spectrum is the same its the same. But they could be full of it...HELP!!!!!!!!!!!!!

I know exactly how you feel, I posted a similar question on lighting on Reefcentral, here, and asked eveyone I could find at the LFS's. MH is recommened so much because it's very intense, works with deeper tanks (over 24") etc.

About all I can tell you, is that I have BTA anenome's doing just fine under my lighting setup, and a few SPS corals as well, both of which you usually see people saying the "need" MH lighting... Well they need "intense" lighting, how you get that intense lighting, is up to you. Clams might be a differnet story, though I have read a few posts by individuals saying that they are keeping clams under VHO or CF lighting (lots and lots of it).

In your situation you may be best off by purchasing MH lights, or you might be able to get away with CF, I wish there were easy answers, but the debate rages on.

The best I can do for you is direct you to search www.reefcentral.com and here for lighting, read the websites of the manufacturers, and just read read read. It took me almost 4 months to finally "pick" CF lights for my tank.

I hope this helps

[nikesmashing]

Well I am going to get a MH but i already have to neet CF units and kinda wana keep. and i was try to prioratise my need for the MH

[DAC]

I had a whole bunch of regular florescents on my tank and all the soft corals, star polyps and "plant" life was doing great. when i put on my Mh all the plant life died adn the corals stayed about the same. The room got a bit hotter, the tank got WAY to hot and the room WAY To bright. I am going to try my luck with CF on this new tank of mine,

[nikesmashing]

Well I'm getting ready to add a 175 watt HH with a XM20K bulb to my 2 130Watt CFs do you think this will be enough light for a 54 gallon corner tank? Please give me a yes or NO. Don't wana spend money on somthing I don't need or is not enough

[VWD]

That will be good , I think what You have now is weak adding the MH will help even a 250 watt is better ,

[yardboy]

I think the primary hangup here is trying to relate wattage to intensity. The wattage is merely the amount of power it takes to run a bulb, not how much output it has. Metal halide lights are much more efficient at producing light, even though they do produce a lot of heat also. Metal halides are MUCH more intense that a CF. The question of if you need them or not depends on what type of livestock you have and want in your tank. Small polyped stony corals will do much better and grow more quickly, and retain their color better under metal halides, than they will under CF's. I had zoanthids growing like weeds under the metal halides and VHO's of my display tank, but when I fragged them out and put them in my prop tank under CF's their growth just kinda stalled out. Most softies will grow well under CF's, but in my experience, the more intense the light, the better. I've used all types of light (I'm even about to rig up a greenhouse and use sunlight) and in the end, in my main display, I've got metal halides and VHO's.
Head out to the beach in the summer at high noon. That's what corals see every day, every year, since they first evolved. Which is closer to that intensity, CF's or MH's?

[yardboy]

Originally Posted by rottielover

Just in case your wondering what I'm talking about, here is a link to the light fixtures I purchased.

http://www.current-usa.com/products/orbit.html

I sent them an email back in Nov, asking if they were going to post some PAR data, they told me in the reply that they were working on compiling it, and I should look for it 1Q 05 (by march).

I can assure you rottie that the PAR rating on a metal halide bulb will be higher than any fluorescents.
Also, on the calculation about the relative costs of fluorescents versus metal halides, I've got a 250W XM 10,000K MH bulb that costs about $60 and lasts 1.5- years. A 55W 10000K PC bulb costs about $30 and lasts 8 months to a year. Doesn't even require me to pull off my shoes to realize that calculation favors metal halides. Your calculation might differ slightly, (cheaper CF's, more expensive MH's, longer or shorter burn times) but they still win out on price.

[nikesmashing]

I have just discover all of this. man this hobey can have some costly learning curves

[yardboy]

That's where reading, looking, asking and thinking come into play (Oh, that I'd used all those when I first started) and clearly deciding what it is you want before you start, so you can get exactly what you need the first time.
You are right, though. It is an expensive hobby, especially if you can't or don't want to DIY.
Reminds me of a couple I saw in the lfs, had seen a 100 gallon reef at a local restaurnt and wanted one. Asked the store manager how much to have him set one up in their home. $7000, he said without a pause. "Okay, Do it" they said, and I staggered home, wishing I had that much disposable income.

[Ace's Reef]

[quote=rottielover]A MH light works like your typical light bulb, it has a filiment that "burns" to produce the light. CF


The metal halide does not have a filiment it has a glass bubble inside that is filled with mercury metal vapor and also indium scandium and sodium. If the mh bulbs had a filiment they would just fire up like any other bulb. The mh bulb takes 10 to 15 minutes to come to a stable state when it is warming up it is melting the stuff inside of the bubble. when you have a higher k bulb the mixture of metals inside the bubble is greater giving you the bluish tint or a yellow tint.
The bottom line is that mh are more intense and penetrate deeper in water and do not lose there intensity as much as cp or vho will.
But every experienced reef hobbiest like myself will tell you that it depends on what you plan on keeping in your tank!!
I have had metal halides on my tanks for years and would never get anything else. I now have a 72 gallon bow front with 2 250w and 2 96w pc. Thats around 700w and = 9.7 watts per gallon. But i keep sps clams and softies every one is thriving.

Ps in my 13 years of this hobby and using mh i have never had to use a chiller on any of my tanks just 4 inc fans in the canopy.


ACE