Lighting 101

  • #1
Let's shed some light on the subject !

Lighting is one biggest investments you will be making in setting up a new tank next to your tank. So let's look into the different types of saltwater aquarium lighting.

There are three classes of lighting, fluorescent, metal halide and LED.

Fluorescent Lighting:
Power compact (PC): multiple, sometimes folded T12 fluorescent lights. (T number is equivalent to 1/8In diameter bulb so T12 is 12/8 or 1.5 in diameter while T5 is 5/8 in diameter) Only one end cap per bulb. Good lights for fish only but not good for corals. Cheap front end cost. Expensive bulbs, 10-12 month bulb life.

VHO (Very High Output): Disclaimer; I never really considered these for my tank, so I don't know too much. T12 fluorescent but overdriven I believe. (Overdriven is when you pump more wattage through a lower wattage bulb = more intense light but shorter life) 2 end caps. Bulbs moderately priced, medium front end cost, Good for fish only or reef tanks.

T5 HO (hight output): 5/8 in diameter bulbs, slightly higher front end costs, bulbs last longer, and are cheaper. Runs multiple bulbs on either single or separate reflectors. Separate reflectors can increase light output by up to 40% Also run fewer watts for same light output = lower electricity bill. Smaller bulb means more bulbs in same area = higher light output. Great for corals tanks less than 24 in deep. PAR (light penetration through water) falls off after that. Probably overkill for fish only tanks. Also runs slightly cooler than the rest.

Metal Halide Lighting:
MH/HQI (metal Halide): Point source bulb, High wattage, very high light output/intensity/PAR. Expensive front end costs, bulbs, etc. Run hot! Great for all high light animals (Acropora/clams/SPS/anemones etc.)

LED Lighting:
LED (Light Emitting Diodes): High power LED lighting. Very expensive front end costs. This is new technology and some claim has a few advantages over conventional aquarium lighting. LED lights can run for up to 50000 hours. This means the LED’s can run for about 11 years with changing bulbs. Also LED's have a cooler operating temperature than fluorescent and metal halide light. Another good thing about LED's is low UV radiation output. LED's also produce water shimmer like a MH bulb. This is something you don't get with fluorescent only tanks.

Most saltwater tanks run a combination of MH for the daylight and either VHO/PC/T5 for the blue actinic spectrum. But you can do any of the above. It really depends on what you want to keep and how much you are willing to spend.

par = photosynthetically available radiation.
Most lights are designated to have a wattage rating, but this doesn't really mean much. 130 watts of power compact lighting is nothing close to 130 watts of metal halide. How much par you want is dependent on the kind of livestock you plan on having. If you have mushrooms and such, you don't want too high of a par rating. If you plan to have clams and sps, you want a ton of par.

I remember reading somewhere a test between a 110W 10K VHO, a 96W 10K power compact, and a 54W 10K T5HO using an SLS parabolic reflector, and they were all somewhat similar in PAR output. That would make the T5HO put out nearly twice the PAR per watt of the other two.
  • #2
Thanks for writing this
  • Thread Starter
  • #3
Thanks matt6765. I'm also working on one about color temperature (Kelvin) bulbs.
  • #4
Oh cool!
  • #5
ah thankyou!!! This has cleared it up a little - but i'm pretty stupid, so I'll ask the lady in the lfs to help when the time comes
  • #6
Can you please comment of the usefulness of T-8 lamps? Their reduced diameter (compared to T-12 and T-10) allows somewhat easily affordable DIY retrofitting using standard lamp assemblies covers. I've been able to boost life in my planted Freshwater tanks by combining this type of upgrade with CO2 injection. I though they might work for SW... (I mean the lights not the CO2!).

I've had some difficulties finding info on the use of T-8 (hopefully in near future we will see better straight T-2 lamps) in SW. Most articles and threads I've read (still have a lot of reading pending to do, I'm a total newby in SW) seem to compare T-12 (Normal Output) with High Output, Very High Output (passing through Overdriven options) to Power Compacts, T-5 and from there to MH et al.

Thank you
Santo Domingo
  • #7
so what kind of lighting would you put on a 55 gallon that's 19inches deep, could I get like 2 16 inch bulbs and put that on the 55?? my 55 gallon is 4 feet long.
  • #8

I'm moving your post to create a thread of its own. This will help you to receive more responses. This thread is a bit old and I want your post to get all of the attention that it deserves.

I'll post the link to your new thread here in just a moment.
Here is the link to your new thread:

  • #9
Lighting 102: Most of your photosynthetic animals depend on the higher kelvin temperatures. That is: more blue. One of the benefits of T5HO lighting is that you can add different types of bulbs in order to gain the full spectrum. A common misconception is that to maintain the harder corals one needs metal halides. This is not necessarily true. One needs the right lighting spectrum for the particular coral.

Certainly the PAR from a MH will benefit a coral at the bottom of a deep tank better than that of a T5HO. Yet if that light is not of the right temperature it is nearly useless.

There seems to be a growing movement among reef owners towards T5HO lighting over PC's and I don't know anyone who uses T8 or T12. Many manufacturers are also moving away from creating Metal Halides due to their power consumption. Thank the Europeans for this, as high energy costs have priced MH's out of the market.

This seems to be the driving force behind the advancement of T5 lighting in recent years. In fact, there is little that a MH can do that a T5 cannot, depending on the depth, of course. On the other hand, you gain so much versatility with the T5's that you can't get with the MH's.

With MH's you are stuck with usually two lighting temperatures: Whatever the bulb is, and whatever complimentary lighting comes with it (actinics, for example). With T5HO there are many more options to choose from.

Still, nothing can replace a MH for larger, deeper tanks. Their intensity cannot be matched by T5's. Some say that LED lighting can match it, but they are priced way out of the market as of now, so it's a moot point.
  • #10
I use 4 t12 VHO's in my 90g reef and I have to say it does a lot better than I would have expected.

I think T12's a very under rated compare to others. I was looking to up grade to 8 T5's in this tank, but the 12's have done so well. I don't think I'm going to up grade now.

Yes I know T5's can do what T12's can at half the wattage and I still wouldn't put my calms in the 90g with the T12. And who knows the corals may grow crazy with T5's. But I'm still very happy with T12's in this tank.

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