Dunno lah. Not I choose one wat. They choose for me and I take later. Will have a couple of rocks basically to replace the US zoas that melted away over the last 2 weeks. just now dipped another 2 US zoa rocks that were melting in Coral RX Pro and found a lot of teeny weeny god knows what in them.
Now I'm thinking it could be a good idea to re-dip all my zoa rocks again seeing that a 1 time dip in coral RX doesn't seem to be 100% effective. Could be that I didn't dip my live rocks also...