400W Radium Metal Halide Bulb

Are Metal Halides Making a Comeback? A New Review of an Old Product

Ok, today LEDs are all the rage so you may be wondering why I am doing a review of a metal halide fixture, especially one that has been around for a number of years. Well, here is the story…..and I am sticking to it. When I pondered what light fixture to use for my new 187 gallon tank I gave LEDs some serious consideration. I had been out of the hobby for a couple of years but I still followed all the latest news and trends, a sign of a true reef-aholic! Nonetheless, on the lighting front it was obvious manufacturers had shifted their efforts away from metal halides towards LEDs.

This presented a dilemma since I have always used metal halides on my SPS dominant tanks. You see, I typically don’t embrace change well and switching to LEDs would be a big, big change. On my prior tank I used a 6′ Sfiligoi light fixture that housed three 400W Radium bulbs and eight 39W T5 bulbs. The colors and growth of my SPS were fantastic and the fixture was a big part of that tank’s success.

sps dominated reef tank

Was it time for me to get on the LED bandwagon and say goodbye to halides? Many reef keepers have beautiful tanks lit by LEDs but my gut and some anecdotal evidence about LEDs led me back to halides. In my opinion, LEDs don’t have the same punch or giddy up to grow colorful SPS at the same clip as halides.  I know, I know. Many folks using LEDs will disagree but this is just my un-scientific opinion. My two cents if you will. Anyway, time to get off of my metal halide soapbox and do the review.

The Giesemann Spectra is a top of the line light fixture that combines both metal halide and T5 bulbs in a smart looking, high end hood. It comes in 2′, 4′ and 6′ lengths and is sold without a ballast. My review is based on the 2′ model, which is paired with a Luxcore switchable ballast. It’s called a switchable ballast since it can accommodate either a 250W or 400W bulb, a major plus if you want the flexibility to try different wattages. As an added bonus, you can also overdrive either bulb with a 250W HQI or 400W HQI setting, something I used to do with the 400W bulbs on my Sfiligoi fixture.

luxcore switchable ballast

Is heat a concern with this ballast? In my experience the answer is no. I have two Luxcores sitting side by side (I have two 24″ fixtures) and the heat they throw off is minimal.  The hood does generate some heat over the tank but it is not a big issue since I have an open top tank. Buying this fixture without a standard ballast is a plus in one regard since it provides aquarists with options. However, a downside is the extra work required to wire the light fixture to a ballast. No wiring diagram was included with my unit so it took some back and forth with the distributor to figure it out. Here are the details:

Wiring Instructions To Connect Giesemann Spectra To Luxcore Ballast

  • MH: Connect Blue wire from fixture to Black wire from ballast plug.
  • MH: Connect Brown wire from fixture to White wire from ballast plug.
  • MH: Connect Green/Yellow wire from fixture to Green wire from ballast plug.
  • T5s: Connect Grey wire from fixture to White wire from 16 gauge power cord (sold separately).
  • T5s: Connect Black wire from fixture to black wire from 16 gauge power cord (sold separately).
  • T5s: Connect Green/Yellow wire from fixture to Green wire from 16 gauge power cord (sold separately).

As for the fixture itself, the quality and craftsmanship are second to none. Giesemann has a reputation for high end fixtures and this unit earns five stars with its premium parts and powder coat finish. Both the halides and T5s have separate high gloss aluminum reflectors that do a great job spreading light, although the Giesemann halide reflector is slightly smaller and inferior versus the reflectors in my old Sfiligoi fixture, a moot point since the Sfiligoi halide fixtures are no longer available.

giesemann light fixture metal halide spectra

Overall, this is a top of the line metal halide/T5 fixture that is easy on the eyes. The real proof is in the performance and thus far I have some happy and healthy SPS frags well on their way to being beautiful colonies. Yes, I am old school but I like to stick with what works. Are metal halides making a comeback among SPS enthusiasts? As I mentioned in the beginning, the answer is no if you look at what most manufactures are focusing on.  However, some folks such as myself may beg to differ based on first hand experience.

Additional Resources

If you would like some help with a new tank build, including help designing a custom aquarium, or help re-configuring your current setup then you can visit this page for more information. And if you are looking to add some equipment, I do sell GHL, Pax Bellum, Reef Octopus Calcium and Kalk Reactors and Royal Exclusiv products, including Dreamboxes, which is the equipment I use and recommend. I also sell Reef Brite metal halide and LED fixtures as well as Maxspect & IceCap Gyres.

As for additional insights and information, please explore my many other reef tank and SPS related articles as well as my YouTube channel. For an even deeper dive into reef tank care you can check out my Reef Keeping Master Class. This online course is an immersive and one of a kind educational tool designed to help reef aquarium hobbyists build and maintain a beautiful SPS reef tank. The course is a series of video presentations with some supplemental video from my YouTube channel. There are also quizzes to help students retain and understand the information presented in the course.

Need some frags…..I can help with that as well 🙂 Please visit my SPS Frag store to see what is available.

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