Finally got a new controller for the UV sterilizer, warranty claim took three months to process. Old one had been in service for about a year and a half.
A few weeks later a leak appeared on one of the tank tees. Turned out to be a crack in a threaded connection, probably caused by the pipe plug. The fitting is threaded on the inside (female) and outside (male).
Replaced with a ball valve. The system supplies water to the Virginia Range mustangs.
Western Horse Watchers Association 