From what I have read on The Advanced Aquarist, you need to make sure you are not adding any limewater or a calcium carbonate/carbon dioxide reactor, not sure if you make use of one. You should use water changes to help get back to a normal range and do as you are doing by adding a calcium...
I've been happy with scarlet hermit crabs. They seem to be the least agressive. If you have enough algae, you can try an emerald green crab as well. Nassarius are fun to watch. When you add food to the tank, they pop up out of the sand and zoom all around.
I agree with tangir1. You need to factor in the depth of the tank as well as what you are going to keep in it. You might get some recomendations if you explain what tank you have or are buying as well as what you plan on stocking it with.
I don't think they are the cheapest, but I also purchased from AirWaterIce. They have a quality product and are good people who have been in business long enough to know what customer support is. I bought the dual system that also make very clean drinking water. No more filling the Britta...
A few people in our local club had problems at the end of 2003 with some IO. Since then I started checking my water before adding it and haven't seen any bad numbers. I've only started tested salt from a bag I already had open and since use up and a new bucket I bought and am half way through...
I just think its bad practice to run an add offering the possibility of free product for at least two months after the free product has been used up. I'm not trying to slam Oceanic. I'm offerring my advise to them that people view things like this as bad practice.
I signed up months ago and never got a sample. Considering they ran the banner about the free sample for so long, I don't buy the fact they ran out. They should have taken the banner down if they already had more requests than samples.
PS
Sorry my first post is negative.