Light means live ! Especially in reef tanks stony corals, anemones and other invertebrates need LOTS of light of the appropriate spectrum for good growth. Designing your lightning you should think about the running costs because they are turned on 8-12h a day. Good reflectors and maybe even new technologies like LED might save a lot of money at the end of the day.
A punctiform source of light which gives you a very natural lighting effect (the sun, seen on earth, is also a punctiform source of light)Corals get their UV light only from directly above. Positive for HQI: If your water surface is steadily moving, you get the so called ringing effect HQI Spots available typically available for (150, 250, 400W) and with different light spectrums (yellow, white, blue) For bigger tanks you need more than one HQI spot.
T5 lighted tanks offer perfect conditions for SPS growth, but look somehow sterile because of the missing ringing effect. They have a high light intensity, not only punctiform, but over the complete lighted area. Light comes from all sides (top, left, right, front and bottom). T5-lights often cover the whole tank. Cooling sometimes is even done by ventilators within the lamps. T5 tubes are available in spectrums perfectly matched and can also be combined in several different colors to achieve the light situation you have ever dreamed off.
An emerging technique with several more products expected for the next month.LED-technology has several advantages: