T-5 Lighting was by far the most popular lighting in the aquarium world before the advent of LED’s, but that has not changed the opinions of many ardent Reef and Freshwater planted enthusiasts. The colors that good T-5 bulbs produce in corals is mind blowing. And the low kelvin T-5 bulbs for planted tanks will grow any plants that there are with stunning results! Also the combination of T-5 as an add-on to LED's is extremely popular.