Loading a water Cherenkov detector with a water soluble gadolinium compound makes possible the detection of thermal neutrons, dramatically improving such an enhanced detector's sensitivity to anti-neutrinos fluxes from both nuclear reactors and supernova explosions. But how can the Gd-loaded water be continuously repurified, maintaining its excellent optical properties, without also removing the dissolved gadolinium? A new technology - the molecular band-pass filter - has recently been developed and is currently being industrialized. The zen and the art of Gd-loaded water - including some of the more entertaining bumps encountered along the way to a viable system - will be discussed by the inventor of this technology.