Fluorescent tube substitution question
I could use some advice from fluorescent tube/fixture experts here. My space-limited seed-starting space wouldn't support the use of the classic shop-light solution, so it was setup using multiple single-tube fixtures from Lights of America (simple U-shaped plastic fixture with switch and line cord, whatever the starting scheme is there isn't a lot of weight in the switch/electronics end).
The fixtures came with F20T10CW tubes, branded Lights of America. There are pretty hard to find, and my memory from the last time I purchased one is that it was costly.
A Phillips Altos F20T12/D fits in the fixture (with less air gap between the tube wall and the base of the fixture) and starts. The light color seems very different from the other tubes, which didn't really surprise me.
Any thoughts/advice, pro or con, about using the T12 tube in this fixture? My biggest concern is whether the increased diameter of the tube represents a overheating/melting/fire threat for the fixture, and there may be other issues I don't know enough to ask about.