t-5s last longer than other bubs but not 2 years. heres the low down
Power compact (PC): multiple, sometimes folded T12 flourescent 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 dont know too much. T12 flourescent 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, median 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 seperate reflectors. Separate reflectors can increase light utput by up to 40% (ive heard) 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.
MH/HQI (metal Halide): Point source bulb (like a street light), 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 etc.)
Most reefers 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 (think of the future too) and how much you are willing to spend. I started with PC and am upgrading to a T5 with separate reflectors so that I can keep most anything I want. I could have gone with just about anything but the T5 fit my style better than the others.
but get the t-5s no matter what. they are the best lights besides mh
