Hi Sam,

I'm refining a 2.88 resolution structure and would like to pick waters. I assume the default low_resolution is set to 2.8 Angstroms and so my lower resolution map is not yielding any waters.

Yes, this is correct.

How do I change the resolution cutoff for water picking to be 3.0 Angstroms? I tried adding "refinement.ordered_solvent.low_resolution=3.0" to my command line arguments

This is exactly what you need to do.

and phenix is reading this, but the refinement crashes about 15 seconds in with the message:

================== Extract refinement strategy and selections =================

Sorry: Selection string 'water' results in empty selection (selects no atoms).

I can't tell anything based on the above error message. Can you send me the exact command you used including all parameter files (if any)?

Pavel.