I myself would advise to NOT use the PH up. I personally would go with the crushed coral.If you cannot find it(Look in your lfs's Saltwater/Marine section) Then my next choice would to be baking soda. There's a thread here somewhere with the correct doses of how to do it,which I shall look for for you. The Ph up works,however I found trhat when I added it to existing snails in the tank after water changes,it bothered my snails enough to kill a few small babies and have bigger ones crawling out of the water.Maybe because there was too much difference in ph after the tank had been going for a while?

I personally have had the best luck with crushed coral.It slowly brings your ph up,and keeps it there pretty steadily as long as I do my water changes consistently.What is your tap water ph naturally?.A good ph for snails is about 7.6 or so.