Aquarium Lighting - Metal Halide - Saltwater Reef - Effects and Precautions?

Question

I've got a 24 gallon saltwater reef tank, and I just got in the mail my new 250 watt metal halide system (15,000k). Prior, I've been using a 120 watt compact fluorescent system. My question is what special precautions should I be mindful of as I install this new system:

- Heat?
- UV penetration effecting the health of the fish?
- Dangerous effects from the light on people (the light will be hanging from the ceiling and will be in a living room)?
- Any other concerns?

Thanks.

Answer 1

You'll need to replace the bulbs quite often. Typically, every nine months to a year or so.

Heat is a HUGE issue. You'll need to ensure good fans keep it cool. Monitor your water temp regularly because the lights will heat up the water (especially a 24 gallon tank). Noise will definitely get annoying. The fan motors can get quite loud if the tank's in your living room.
Algae will also become a factor since the lights will definitely promote more growth.
Don't forget that you are controlling the "sun" for the tank so you should consider putting it on a regular cycle so the fish and coral get used to a set schedule.
Water evaporation will happen quicker now, so your salinity levels should be closely monitored too.

Safety issue: I would refrain from running the light when you're not home. Treat it like your dryer... typically its safe, but you never want to leave it unmonitored due to fire hazzards.

Answer 2

One thing to add to Doug's comments is that you should acclimate your tank organisms to the new light gradually. That's a powerful system for a 24 gallon tank, so I'm guessing you're keeping corals, anemones, and/or clams which need the intensity for photosynthesis. But this will be a step up, so raise the light a little higher and gradually lower it so you don't burn your animals.

Since it does produce UV radiation, it's possible to get "sunburn" with them Keep this in mind when positioning the light and try to shield it from any chairs, etc. nearby.

High heat, so monitor your water temperature as well with these.

Answer 3

Lots of people say that metal halides are the best lighting available as they are pretty much the closest thing to the actual sun. Metal halides give off a desired shimmer effect as well. Under a metal halide, you can keep lots of varieties of corals/clams, depending on the wattage. T5 lighting is basically the next best thing. If you're keeping a reef tank then I think a T5 lighting would suffice, because metal halides can be expensive. Metal halides can cause a raise in temperature as they can be quite hotter than the T5's. I think it's all a matter of personal preference, whether you prefer that shimmery look of the metal halides versus the normal look of the T5 lighting.