i used b-ionic with great results when i had a smaller tank...
this kit comes with 3 major items at a great price: http://www.bulkreefsupply.com/Calcium,-Alkalinity-&-Magnesium-Two-Part-Calcium-and-Alkalinity/c1_51/p269/Two-Part-Kits/product_info.html
but like Ian said, get good test kits...overdosing can be just as bad, if not worse, than not dosing at all...