Currently, I have two letters of recommendation that are from professors that have been able to gauge my research potential. From what I understand, this is what programs look favorably upon. The problem is that I need one more LOR, the only person I feel safe with writing such a letter would be a post-doc student that I've been working with.
My question: I feel like this would be the best person that could help me out with a recommendation letter, but will the fact that he is a post-doctoral student, rather than an actual professor, hurt the value of the LOR? I mean, I have no problem with asking for a letter from a professor whose class I did well in, but he/she wouldn't know how I perform in the lab.
Any input would be appreciated!
-Mick