If you buy another one of these, maybe skip the bleach step next time. It's just a wild guess, but bleach and dye usually don't go well together. You might have damaged some protective coating by bleaching the thing, or weakened the adhesion of the dye to the resin so that it came off in the water over the period of a few weeks.
Personally I prefer to use natural driftwood or rocks in preference to resin ornaments.
Best of luck!
Personally I prefer to use natural driftwood or rocks in preference to resin ornaments.
Best of luck!