pretty sure FOG doesn't drop water stones but either way the only easy stones you can get is water/fire from IOP the rest come from HB or dark water dragons making them pretty near impossible to get for a bh although im sure the sws would be very welcome
agree with nanashi. and littlebunny, be very careful when handling those water dragons, specially as a FS, they are a pain to bring down. bring adequate support. good luck. do report if you were able to acquire earth/water.
you can trade fire for water so that shouldn't be a problem
i know a WS who does the dragons so i guess FS should be able to do it too since i doubt the golem was tanking... it'll just be a bit slower