metal halide vs. vho

[ERIC5555]

i have been researching this subject for quite some time now. i havn't really found any right or wrong answer. does any one have any experience, or opinion about either that they'd like to share?


i have been thinking about building my own canopy and buying a retrofit kit

[Aaron1100us]

heloo, welcome to RC. it all depends on what you want to keep. MH is more intense than VHO.

[DJ88©]

The only similarity that really exists with the two is that they produce light.

One is what is called a point source(MH) and the other is a more linear lighting source(VHO).

Mh by the nature of it's design can produce much more intense light which is great for corals and other light loving critters. :) VHO's aren't as intense but can be suitable for many types of tank/coral combinations.

There really isn't a right or wrong answer for what to use.

It depends on what you can afford, want to keep and want to work with.

You can have a sucessful tank with either. But with the more light demanding creatures you are giving the tank a better chance with MH.

[jdieck]

I just responded a similar question in another thread which turned more like a disertation than a post. A little long but here it is:

Different strokes for different folks and I am not referring here to us aquarists but to the corals.
So here I go again....

What makes this hobby atractive to me is the variety of animal life from the reefs but as such it means I need to meet their espectations regarding their environment. Although most species can adapt and survive there always be in my opinion a narrow range when just survival turns into triving, growing, multiplying and so.
If we think about a mixed tank (and seems a lot of us do) you can go two ways, one to set up your system and then look for species that will trive within the conditions provided by your setup or you can decide which species you want to keep (recommended to save $$ as we seem to change expectations as we learn) and then adapt your system to the species known needs (and I say known because there are many that we are still experimenting with).

Setting aside the non photosynthetic corals basically the coral's lighting needs can be narrowed to a combination of intensity (PAR) and Spectrum at the coral location. Sometimes we have the the tendency focus on the lamp and fixture itself and tend to disregard that the water, tank covers or braces, fixture lenses and reflectors all can affect the end result of PAR and spectrum if measured from the coral position.
We tend to talk about sps requirements of high intensity lighting but yes, generalizations are just "guidelines" and sometimes misleading. What do watts per gallon has to do at all with PAR and Spectrum?? With 400 or so species of acroporas alone, deep water, reef tops etc. who is to say all acroporas being sps need high intensity? Corals do not feed on watts but on the other hand different wattage can provide us with the the PAR intensity and the bulb's temperature provide us with the spectrum we need to fulfill the requirements of our specific corals.

I would venture (risking to be flamed) to say that a 10K 400 watt Metal Halide may not be very suitable for an Acropora whose usual environment is deep water and as such require lower PAR more distributed difusse lighting toward the blue spectrum band now placed just a couple of feet from the surface of the aquarium.

For this coral my preference would be a VHO, PC or T5 toward the blue spectrum so I can better imitate the depth of the natural environment.
Now VHO, NO, PC may not be right for a maxima clam whose natural environment is close to the surface on the reef tops near the ecuador where the sun hits stright down but conviniently placed at the bottom of a 36" depth aquarium so we can see better the color of the manttle.

This line of tought has taken me to the conclusion that if variaty is what I want in my aquarium I need to provide different environments within the same box so I am driven for a combination of Metal halides and Power compact or VHOs of different wattage and spectrum. This combination of lighting together with a combination of different powerhead locations and sizes and the rockworks arrangement increases my flexibility (and surely my $$$) to meet a larger range of specimens needs. A chilli coral upside down under a cave with high flow, a coco duster shaded by the side of a rock on medium flow, a deep water acropora in the middle of the tank under a 20K MH or an euphylia hanging on the side of the rockworks shaded from the metal halide in the center top but lighed by the suplemented 7.5K and 03 actinic PC on the side top of the tank.

Once I have achieved the combination to meet the requirements then I can think in optimization. If I can get the same PAR and spectrum from a MH, PC or VHO I would look for the one that will give me the best performance meassured as units of par per watt consummed (operating cost) and Fixture/ballast/lamp cost per unit of par generated. (investment cost).

In conclusion I do not think neither one system is the best or the worst, it is the wonderful variaity that can be achieved by the combination of two or more what makes it very atractive to me.

Hey; we want a pink or red coral? why no to supplement with a pin pointed narrow beam of a low voltage hallogen red reflector? Well... although it might be atractive to some it will not count for others as the red will not be the natural color so if natural is what we want let's continue trying to imitate natural enviroments. The means? Who cares as long as we could do it, and do it within our $$$ posibilities.

Happy reefing everyone!

[Entropy]

Honestly the question shouldn't be either or, it should be how much of both? :D

I have both and they are far better together than either are by themselves. I don't think there is anything better (other than the sun on the open ocean maybe) than 10k metal halide bulbs and VHO actinic.

[odyssey1]

I agree with Entropy I use both. I use the mh for intencity and the VHO for the bluish tent together they make in my opinion the best way to mimic the sun. If you plan on keeping corals mh is a mush in my opinion. Also you will not beable to get the ripple effect with any other bulb than the MH.

[grahxen]

I dont see why everyone keeps bringing up the fact that MH gives ripple lines, this is for looks and quite frankly some people cant stand them. They make me dizzy for 1. I have had VHO tanks with SPS, CLAMS, LPS, softies etc. MH is yes the best light, but its also very over rated. Ive seen just as many successful VHO tanks as well as MH tanks. You can get SPS and clams to thrive in VHOS as long as you have plenty of them. I have 6 VHOS over my new 50 oceanic and I can keep anything. With well over 15 years in reefing ive had my share of tanks and lighting setups. I usually reccomend MH to tanks that are over 21" tall. Or if they want to keep only SPS. For mixed tanks, i like the VHO look, but thats only my opinion.

[NIXONNOXIN]

"...ripple lines, this is for looks..." Not quite true. These are converging light rays caused by the surface water bending the light rays, like a magnifying glass. Not to mention, that is what you see in nature. Go diving sometime and you'll realize how artificial VHO only lighting appears.

I would agree both is the best of both worlds. Running both MH and actinics on different schedules is like having two tanks in one.

[pbs911]

I went throug hthe same internal debate. I am no expert by any means. I wanted to avoid upgrading in the future if possible. I went with 2 400 wMH and 2 VHO. Before you order do your research. When selecting MH ballasts lookat this thread (http://archive.reefcentral.com/forums/showthread.php?s=&threadid=201570) to know what will best suit your needs and you alternatives for replacement bulbs.

[MalHavoc]

I've discussed these "ripple lines" in another thread. They are correctly called "caustic" lines and do indeed contribute to the lighting demands of corals. The light at these lines can be many times more intense than the MH bulb all by itself, and can dramatically increase the rate of photosynthesis.

[MiddletonMark]

Just to chime in ... I tend to think that the `high watt' MH's are overkill unless you are keeping a small range of things ... high-light acros and clams. Which can also be kept under other MH bulbs, without the heat issues or power bill.

As for which light - I find consideration of bulb replacement costs to be a big factor why I like my MH. When I look at the # of bulbs in a fixture for equal watts [although that does not mean equal light] ... MH is much much cheaper.
VHO or PC are great for actinic, but for the `main light' I'd suggest MH for the flexibility it gives. As I've just upgraded my 36x18x21 58g tank to 2 x 175w MH + 110w PC actinic [from 1 x 175w MH + pc's] ... I'm thankful I wasn't all PC or VHO so upgrade to higher light for more clam/sps space was cheap and easy ... had fans, etc].