Ok thanks for info and yeah mixing them tubes in with others makes perfect sense as like 80-90% cheaper or for a fuge etcI use some GE 6500k. They look like 6500k and hard to describe to people who have not seen them, sorry, They are daylight to the eye, but can pop some reds and blue. Most people consider them too yellow, but I don't care since they are on fuges and to grow coral. The coral that grows under them get great color, the bulbs just don't show them off very well. I usually buy them a case at at time from somewhere. Most people mix them in with other bulbs. I do like the look at 50% 6500k and 50% true actinic - both of these bulbs give spectrum that most other T5s bulbs do not have, plus what they do.