The differences between Mercury Vapor and Metal Halide

[dr.diggler]

I was wondering if anyone is using a mecury vapor bulb for there lighting in a saltwater reef system compared to a metal halide.. Can you also explain the differences between them.. Could i get away with using the mecury vapor bulb.

 

[Biggen]

I think the only reason one doesn't see many MV aquarium bulbs on the market is because MH works fine. Why go with another High Intensity Discharge (HID) bulb when there is no reason to?

Also, from what I have read, the spectra output of MV is not continuous. I would bet plant and coral life would not appreciate that. Also their PAR is much lower than a comparable MH bulb. In other words, they don't give off as much light.

I am not really well versed on how they operate. I have a general idea but nothing that would offer your any good knowledge. Perhaps someone will know...

 

[Bang Guy]

The biggest difference besides the internal gas use is a starter. The MV have an internal starter and the MH have the starter in the ballast.


The HID lights I use are all Mercury Vapor. The bulbs I use are 6500K and put out significantly more PAR than Metal Halide bulbs. Up to twice the PAR in some cases.

 

[dr.diggler]

Bang Guy, you are saying that the MV is stronger than the MH.. I am seeing that the MV is also cheaper than the MH.. Just curious because the two replys i got are contradicting each other

 

[Bang Guy]

It depends a lot on the bulb. MV put out more light for the energy used but very few MV bulbs look very good. I use the Iwasaki DL bulbs. The light is white but for looks it should be supplemented with Actinic.

The higher Kelvin MH bulbs look great even by themselves and the corals tend to color much much better but the PAR is lower. HQI tend to be the top MH performers.

If money were no object my ideal lighting would be 400 watt 12000K HQI lighting supplemented by VHO Actinic.

 

[Biggen]

I was always under the impression that MV lights put out less light than MH. Like you said, I guess it depends upon the bulb.

 

[Bang Guy]

Typical MV vs MH comparison

Dana Riddle compared the 400 watt Iwasaki (6500K) to the German/Hamilton 400-watt metal halide bulb (10000K) and the Coralife 400watt Reef MH (10000K).

Iwasaki PAR = 3798
Hamilton PAR = 3040
Coralife PAR = 1850

This is a significant difference between to high quality bulbs.

 

[Bang Guy]

More miscellaneous info:

The Iwasaki cost about $75 and the Hamilton about $150.

Iwasaki bulb maintains spectrum for 24 months and the Hamilton about 12.