• Why only MG

  • Christopher7213

Greetings to all. The question is this: why are metal halide lamps specifically used for lighting marine aquariums? 1. They are bright and beautiful, pleasing to our eyes. 2. They are vital for aquatic organisms. I would also like to add one point: I have acquaintances who are passionately obsessed with indoor exotic plants, and they firmly assert that nothing is better than lighting from sodium lamps (DNaT-DNaz). Let me explain - these are gas-discharge lamps like metal halide (their ballasts are identical), but their spectrum is closer to red and they emit a yellowish light (note the streetlights in the evening - those are sodium lamps, not to be confused with blue mercury lamps). They claim that plants thrive 100% under this spectrum, blooming, smelling, and reproducing! Terrestrial plants are not much different from aquatic ones, and indeed, our sun emits a more yellow light than white, so perhaps the inhabitants of marine aquariums will thrive better under a spectrum closer to sunlight? I apologize if this has been discussed; please close the topic.

Rodney7316

Um... well, ask your acquaintances what will happen to simple algae if they are placed under a yellow/warm spectrum at 1000-4000 K. Then check out one of the threads "overgrowth!! what to do!!???" and other complaints about diatoms/cyanos/etc. And establish the cause-and-effect relationship. Marine aquariums and plants are still different topics. P.S. Some super aquariums keep T5 lights and don't want to hear about mg at all... so, to each their own.

Stephen5857

So, do overgrowths and protozoa make us abandon the spectrum closer to the sun? I thought that in a balanced system there is no place for protozoa and that lighting is not the most important factor; there are many other factors!

Jennifer7159

I have a little experience, just a couple of years, maybe others will say something different. In my opinion, there is no place for such a spectrum (2000-4000 K) in a reef aquarium. In a planted tank, sure, I have a 4000 K and 6000 K lamp myself. But in a reef, no.

Christina9947

I just got acquainted with the rhyme, that's why I'm asking.

Alicia5489

Check the forum, there are entire threads about lights on metal halides and aquariums under them... but for freshwater. The main problem is that the lamps give off a yellow light, but for freshwater plants, that's just right. Since when did 4000K become closer to sunlight? Have you been underwater in the sea? Is there a lot of yellow there?

John3335

and the banal physics, the wavelength of red and blue, I mean in the context that a ray of light, passing by a terrestrial plant on its way to the coral, must "pierce" through some thickness of water, then the body of the coral itself, and only after that reach the zooxanthellae. Although it was hinted to you earlier that there is also an underwater part of the iceberg in terms of biochemistry and physics, which is no longer banal.

Charles4157

Thank you all very much! There is a lack of conclusions about what optimal spectrum the reef needs, as the range is quite large from 6000 to 20000 K.

Adam4310

Color temperature (K) is very weakly related to the spectrum. Roughly speaking, it is the temperature of a piece of iron heated to a certain color. So it is a rather arbitrary indicator.

Judy

There is no optimal amount. One could argue and write more than one page about it. The range is just a bit narrower - 10,000-20,000K. I would recommend starting with 10,000 - 12,000K.

Steven757

100%. Even different corals (whether photosynthetic or not) require different spectra. So we either set an average and don't worry about it, or we select it through trial and error specifically for our system. In my opinion, a shift in spectral characteristics by 10-20% in either direction does not significantly affect the life of aquatic organisms, although it is essential to use ONLY specialized lamps (if T5) or to use metal halide lamps with a margin.