found a bit about t5 lights here.... have a little read .......
What are T5 Fluorescents and why are they so popular for growing plants?
Fluorescent Lamp technology has become very efficient in converting energy into light output in recent years. We are now seeing a higher watt to light output ratio from the T5 fluorescent than is experienced using High Intensity Discharge (H.I.D.) systems like Metal Halide. Each four foot T5 lamp produces an amazing 5,000 lumens per bulb! This is incredibly bright and represents a huge leap for fluorescent technology. Antiquated T12 fluorescents (your standard "shop-light" fixture) and the popular T8 fluorescents emit around 2,600-3,000 lumens per 4’ bulb. T5 Fluorescent’s light output is even higher than Metal Halide’s intense bright light as Metal Halide bulbs produce around 80 lumens per watt. T12 fluorescents emit around 65 lumens per watt and the T8 fluorescents emit about 81 lumens per watt. Compare that to the T5’s outstanding 92 lumen per watt ratio and you now see why T5’s are truly the next generation in grow lights. Metal Halide and T12 and T8 lamps can lose as much as 50% of their initial light output over the life of the bulb. So without regularly changing your halide/sodium bulbs, your plants could be growing at "half speed". T5 fluorescent bulbs also hold their lumens longer than Metal Halide / High Pressure Sodium and other fluorescent bulbs meaning they stay brighter longer. This means you can be assured your plants are receiving the proper amount of light over the lamps life.
Many independent tests have shown the T5 Fluorescents outproduce higher wattage Metal Halide systems. The reasoning is this. High Intensity Discharge (H.I.D.) bulbs including Metal Halide (MH) and High Pressure Sodium (HPS) emit light from a very small source - a two to four inch arc tube inside the bulb. The light is very intense and needs to be spread across the entire garden from this one small point of light. So, not matter how effecient the reflector, the light still has to travel a distance from the arc tube and across the garden losing light intensity along the way. T5 Fluorescent lamps emit light from along each 4’ section of each of the 4 bulbs. This is a much larger light source spread over a much larger area. This allows the grower to place the T5 fluorescents very close to the plant canopy while still achieving the light spread across the entire garden area. Placing the light closer to the plants equates into very high light intensity. Metal Halide’s small arc tube also gets very hot and if placed too close to plants it will actually burn them. Since T5 fluorescents have such a large area of light source along the bulb they also emit considerably less heat than Metal Halides and thus can be placed very close the the tops of your plants. T5 Fluorescent bulbs also come in a variety light spectrums (eg. "warm/bloom" and "cool/growth" spectrums). This allows each grower to customize their light for the type of plant growth desired. Use all "cool" 6,500 Kelvin Daylight Spectrum bulbs for lush compact vegetative plant growth or "warm" 3,000 Kelvin Red Spectrum bulbs for explosive flowering plant growth - or mix the both "cool" and "warm" bulbs to create a truly balanced light spectrum!
In conclusion
T5 fluorescents are much more efficient than their older T12 and T8 fluorescent counterparts and Metal Halide producing considerably more light output per energy used.
T5 Fluorescent bulbs stay brighter longer than Metal Halide all other fluorescent bulbs.
T5 fluorescents have a much larger light source and run cooler compared to Metal Halide and High Pressure Sodium bulbs.
T5 Fluorescents can achieve very high light intensity levels and can be placed very close to the plants.
T5 Fluorescents give growers the best control over what light spectrum they wish to use for their plants specific stage of growth.
T5 Fluorescents are the next generation in grow light technology
