The high active water resistivity took a long time to recover after the upgrade to the water cooling circuit. The system needed about a month (from end February to end March) to recover to nominal values. See attached plot of archiver data.

TM1 has now been connected in ITW and the water resistivity remains > 8 MOhm cm, which should allow normal operation. However, the resin is suspected to be approaching end of life. Work is ongoing to get a new replacement resin tank.