Welcome to the forum Dan,
I initially filled my 22K gallon from a single well in 1997 and the only problem I had was silt and mud from sucking so much from the well. Tt is easiest on a well pump if you run it continuously assuming you don't run the well dry. I ran three garden hoses right from the pressure tank so the pump never shut down. Cycling is what kills well pumps. I filled mine in the fall so it had all winter to let the muck settle. If you're gonna do this save a bunch of drinking water ahead of time in case you stir things up. I don't use my wells for the pool now but top off from a small stream. I guess I was lucky in that I never checked for metals and never had a problem with the initial fill.
Al