sanitizing tanks problem

Just asking but what exactly do you mean by "rinse?" Did you run a few gallons through the system or did a rinse consist of completely filling the tank and then completely draining it? And did you drain it at the tank drain or run the water through the system? A complete fill and flushing the lines would be necessary to touch all surfaces with clean water.

I had a similar problem once. While it may be aggravating, I didn't consider the foamy water to be unsafe to drink. Cities add chlorine to their water all the time.