Evaporating chemicals?.. Regarding as to leaving the rez uncovered and open to the air (from fountain/waterfall), would this be an unwise idea?.. To have your precious distilled water and Water Wetter evaporating before your very eyes? Or is the Water Wetter a heavier type of chemical which does not evaporate, requiring you to only add more water as needed? UV dye as well.. will this evaporate if left in an open rez? and finally, Should this "dual" rez setup to convert my sump pump to inline work or will this be too restrictive to flow??