Cleaning of tanks after use

I have a march pump and am drawing up a CAD schematic of how I want the piping to work for all tanks. The one thing I am stuck on is a drain pipe for using while washing out the tanks after a batch. Should I just be dumping my grain after the mash or is it alright to wash it out of the tank through the pump and out a drain line? Is this bad for the pump? I am trying to setup a pretty autonomous system I would prefer nothing have to move at all during and after brewing. Any thoughts would be great. Thanks!

Unless you have a 2" line, you're going to be dealing with constant clogging, and possibly running your pump dry.
If you're doing the typical 1/2" piping, manually getting as much grain out of the system before cleaning is required.
You can of course make that as easy on yourself as possible with a tippy-dump or whatever else you might come up with.