Water heater flushing.

I have been having this white stuff drain from my water heater tank. I've been draining it while driving home. I've been noticing this powder. At first I thought it was the DE (keeps ants out)from the floor jacks. I made sure to blow any off before I started the drive this weekend. It ended up like the picture. I had a Anode rod for a couple months but switched it to an easier valve to drain it. Any ideas on what to do next? I'm thinking of filling it from the release valve and flushing it out. Thanks