ancientaviator62,
In January, 2008, BA Flight 38, a 777 from Peking (sorry, Beijing) flopped on LHR with the same trouble. I'm sure this FSII stuff is good, but a better idea is to drain the water off before you start.
The Daks out with us always did this every morning. Often got a cupful of water out of each tank (overnight condensation).
D.