I once got some sand from a reefer that was live. I dug through it with my hand and pulled out a Monti on on a frag disk.
After finding, rinsing off and placing on frag tray it has regained color and almost encrusted the disk it was on.
The guy had the sand for at least 6 months and had never bought a monti like I had described. He had purchased the sand from another reefer.
Keep alk around 8.5 and salinity stable and it might pull through no problems. I test all every day.