# Metal Halides vs. Compact Fluorescents



## travis (Oct 5, 2004)

Someone please help me settle this discussion. I've read/heard on too many forums that MH lighitng is strictly a reef aquarium fixture. Correct me if I'm wrong but wouldn't it work just as well for planted aquaria (a la Luis Navarro) in a similar setting. From what I've read MH lighting is analogous to running your planted tank on nitrous. Luis may get away with it because he's a master, but those of us who can't balance our tanks on the razor's edge may regret the investment in a sun-tan bright envrionment. Am I wrong to assume that I should stick with the industry standard CF lighting for my favorite rare cS specimens, or should I consider hiking my photosynthetic bandwidth up to true daylight levels?


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## gnatster (Mar 6, 2004)

BAH!!

I am by no means an expert on lighting and I did not stay in a Holiday Inn last night but a photon is a photon is a photon. 

To bad I don't know enough to delve into the specific differences but using MH is no different then using Power Compacts. You need to keep some things in mind, such as a MH produces more heat. PC's have a better light spread since they produce light on a longer length where a MH is a point source light. You need to keep this in mind when planting, corners are a bit darker then directly under the light even with quality reflectors. MH offers this intangible quality that is lacking with PC's, the water has a certain shimmer to it. I can't quite wrap words around the effect 

I certainly would not call MH at the same wattage levels as PC's like rung on nitrous, it's just different.


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## TWood (Dec 9, 2004)

Directly under a MH there is probably more 'punch' so they can reach deeper, but that's not spread out. Watt for watt both MH and PCs produce about the same amount of light and heat overall, it's just spread out more with PCs. Reflectors and positioning can have big effects on the efficacy of both.

TW


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## skylsdale (Jun 2, 2004)

> Watt for watt both MH and PCs produce about the same amount of light and heat overall,


I have to disagree with this. You can't just look at watts when you're looking at lighting...at least in reefkeeping you can't (the WPG rule doesn't mean jack when it comes to keeping corals). The differences between NO, PC and MH is largely a matter of PAR--basically, the _intensity_ of the light being put out. Halides generally outcompete PC's, unless you've got a 70w halide and 200w of PC. But, if you were to compare two fixtures of even wattages, but one had only PC's and the other was just a halide, the halide has an incredible amount of PAR compared to the flourescent fixture.

This is important in reefkeeping because many corals require intense amounts of light as they are found in brightly lit waters in the tropics. Because halides are a point-source light, they also create glitter lines in the tank as the light refracts through the bends and folds in the water's surface. This acts as a magnifying glass, and punches very intense amounts of light into the corals' tissue, etc. This isn't necessary for plants. We're talking apples and oranges here, even in regards to lighting needs.

Even though I'm a fairly strong proponent of halides over reef systems, I don't see much of a need for them over planted tanks...unless money isn't an issue or the price of a halide system is going to be comperable to a large PC setup. You generally have more heat dissipation to deal with (but that varies), if you're going to go with an HQI or DE bulb, then you have to make sure ot have some sort of protective glass covering between the tank, bulb, and tank viewers so it will block the UV being emmitted, etc.

You can do it, no problem (and the plants will LOVE it)...but it's not a requirement by any means.


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## TWood (Dec 9, 2004)

skylsdale said:


> Halides generally outcompete PC's, unless you've got a 70w halide and 200w of PC. But, if you were to compare two fixtures of even wattages, but one had only PC's and the other was just a halide, the halide has an incredible amount of PAR compared to the flourescent fixture.


Well, if there really is a three to one advantage in terms of 'light' we'd see a lot more use of MH in the places we work, shop and do business. Energy costs being what they are. I'll take your word for it on PAR though, I haven't kept up with the literature on that.

TW


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## turtlehead (Nov 27, 2004)

I thought you can only leave MH not as long as CF so you have less time to enjoy your fish.


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## Kevin Jones (Apr 4, 2004)

I have used PC and MH over numerous planted tanks in the past. Presently i have a 175watt MH pendant over a 60 gallon cube. with this setup i have observed The BEST growth of Crypt species i have ever seen. I have noticed that MHs will produce 'hotspots' in my tanks where algae will be next to impossible to avoid on most plants even with alterations of intensity, photoperiod... yadda yadda yadda. 
I'm using a massive Giesman MH unit on a planted tank in the store i work in (2x150HQI plus two T5 tubes) This unit is very high end, but has its drawbacks. The tank is a marineland 90 gallon surf, the tank has great growth, but the time it takes for algae chaos to break out is greatly reduced compared to the other planted display i maintain in the store which uses VHO tubes. in the VHO tank, i can go days on end without having to worry about rampant algae, whereas the HQI - lit tank can go from great to crap in a day.

I only reccomend MHs for Deep tanks, or in instances where replacing a few MH bulbs is cheaper than Many CF bulbs on larger tanks. I like the spectral output options one has with CF and regular flourescent tubes and will use those two options preferentially before undertaking the tasks associated with a "tank on nitrous" 

just my two cents as a retailler and a hobbyist


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## IUnknown (Feb 24, 2004)

> in the VHO tank, i can go days on end without having to worry about rampant algae, whereas the HQI - lit tank can go from great to crap in a day.


A way around this would be to get a combo setup. Just run the MH for four hours during the day and PC's for the rest. I think the main reason MH are not used in the hobby, is that with planted tanks everyone is looking for the cheapest solution. MH might be more appropriate for larger tanks though.


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## gnatster (Mar 6, 2004)

I admit I am biased towards MH. Yes the price of entry is generally higher then especially when compared with some of more interesting ODNO setups I have seen with inexpensive shop light fixtures. I think they also work best where they can hung as pendants over an open tank too. This allows one the flexibility to adjust the height to suit the needs of the both the grower and the plants. I also think there are certain sized tanks that do better with MH then others. I'd certainly not put one over a 10 or 20 but a 30 cube I think just begs for a 70W pendant. Narrow tanks of less then 18" width I think also are ill served by MH. 

Is MH for everyone, no, it is a viable option that properly applied can assist in achieving stunning results both in the tank and the overall look of then entire setup in your living space.


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## TWood (Dec 9, 2004)

I think the planet is better served by finding ways to use less lighting rather than more. I also think it's just stupid to suffer under the glare of a suspended light fixture in a living space just so you can grow weeds underwater. This hobby desperately needs a reset.

IMO

TW


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## Kevin Jones (Apr 4, 2004)

IUnknown said:


> A way around this would be to get a combo setup. Just run the MH for four hours during the day and PC's for the rest. I think the main reason MH are not used in the hobby, is that with planted tanks everyone is looking for the cheapest solution. MH might be more appropriate for larger tanks though.


well, i agree that MHs should only be used for a few hours a day (as popular opinion would support). My HQI tank only has full illumination for about 5 hours a day. The VHO tank has been up and running for a few years and was setup without the notion of ever including more intense lighting. In fact this is a blessing, the lower level of lighting (~2.2wpg in a 220 gallon) and the aged florabase seem to work well with each other. the swords in the tank flower to the extent where i am throwing away plantlets if i can't sell them and regular prunings are much less frequent (the tank looks good with less work woohoo  )

and as far as wasting energy on lighting is concerned, remember that a 5 minute shower in a typical home will consume enough energy to light your tank for quite some time. not to mention the hot water used in your laundry when cold water detergents will do the job. lighting is far more efficient now than it was a few years ago, what needs resetting in this society are the other aspects of energy consumption petroleum being HIGH on that list and lighting is frequently wasted, but aquarists typically are a small component of that equation when one compares a hobbyist's energy consumption on his tanks to other squanderings of energy in cities.

wasn't meant to be a rant, but i did a fair amount of studying in this area.


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## AaronT (Apr 26, 2004)

I'm in the process of creating a MH/T5 fixture for my 75 gallon tank. The plan is to have the T5s on in the morning and evening and to have the super intense MH lights on for the 4-5 hours in between...Amano style. Is it necessary to use MH lights on a planted aquarium to have success? NO WAY, I've been using ODNO T8's until now and can grow most anything. My reasoning for using MH lights is purely visual. The flickering rays of fake sunshine are simply stunning and unmatched by flourscents.


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## IUnknown (Feb 24, 2004)

> The flickering rays of fake sunshine are simply stunning and unmatched by flourscents.


Yeah, that and the shadows of the fish swimming through the water. So much more natural looking.


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## TWood (Dec 9, 2004)

My guess is that the MH in the middle of the day only, is a reaction to the desire to grow carpet plants coupled with the difficulty in also not growing algae if they are on during the entire photoperiod. Get rid of the desire for carpet plants, and the choice for lighting gets real easy. Now if there were just an easy way to create that ripple effect without the intensity of MHs...

TW


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## AaronT (Apr 26, 2004)

TWood said:


> My guess is that the MH in the middle of the day only, is a reaction to the desire to grow carpet plants coupled with the difficulty in also not growing algae if they are on during the entire photoperiod. Get rid of the desire for carpet plants, and the choice for lighting gets real easy. Now if there were just an easy way to create that ripple effect without the intensity of MHs...
> 
> TW


Nope, I can grow carpet plants using the lighting I currently have without algae no problem. It's purely for looks. Not growing algae has to do with proper fertilization techniques.

Also the more intense light in the middle of the day and less intense in the morning and evening more closely simulates a real period of daylight.


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## Lefty (Mar 11, 2005)

I have almost no experience……. ordered my tank today. I have done lots of research and have looked at tanks in lfss for years. In all my travails aquatic, the tank that looked by far the best was the one with mh. The visual was so much more natural, (first time I had ever seen mh on fresh water / plants ), almost made me feel as if I were looking down into a sunny riverbank. Shadows, highlights, glimmer lines - I will never forget my immediate reaction. Because of that tank I am still not completely sure what I will buy. "Beauty is in the eye of the beholder" but for me, mh is much nicer on the eyes.


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