You JUST posted a message on the reef board about not understanding how to do water changes (about 5 mintues ago), and now you want ot add MOTE to your tank??
Honestly, as I said above, I would not add anything, seriously, NOTHING until you get your water a little better....for a period of at least a month.
Inverts like snails and crabs are very sensitive to certain changes (like salinity). But again, it is your tank, your money...if you want to risk killing things, that is your choice.