If you’ve watched what’s been happening to fluorescent lamps over the last decade, you will have noticed the trend from T12 to T8, then T5 lighting (each number following the ‘T’ corresponds to an 1/8th of an inch in diamater). It should come as no surprise then that with the ever shrinking bulb sizes we would eventually get some T2 lighting for our aquariums. T2 lamps are 7mm in diameter and like the skinnier tubes before it, the decreased diameter makes these lamps easier to drive, more efficient and definitely more narrow. The T2 lamps are rated for VHO (very high output) and by comparison, many of the spiral twist compact fluorescent bulbs (CFL) are T3 in diameter. The largest T2 currently available is just over 20″ long, 13 watts but with up to 73 lumens per watt, these lamps are no slouch in the efficiency department. T2 lamps are not new but the increased Kelvin rating of newer lamps makes them increasingly suitable for aquarium use. The trouble is, with such a narrow tube the lamps are limited by their lengthÂ because much larger than that and they cannot be properly driven. The aquarium designed bulbs retail for about $14, of if you prefer you can purchase the bulb and fixture unit for only $35. We are excited to see these new T2 lighting bulbs hit the aquarium market where they won’t replace high intensity lighting, but at least for smaller tanks and refugiums the new lamp format should raise the bar a little bit.