The bottom of the tank should be fine. I have some under a 400w in a 54g corner with no problems. (It is a 20k rated bulb, though)
If you begin to see them shrink or bleach you can move them into a shady area. I would just keep an eye on them for now. Anything negative that happens won't just happen overnight, it will be something you will begin to notice and have plenty of time to correct.
Good luck :thumbsup: