which test kits to buy?

[toytech]

Depending on what you want for corals you will need to test and dose accordingly , a full sps tank needs daily dosing , an all zoathid tank needs none so buy what your going to test for , don't need to know calcium levels in a soft coral tank they don't care. You can switch salts but again its all in what you want , and lots of people use instant ocean with good success you just adjust the levels of the new salt water before you do a water change . Its what im using and im shooting for mostly sps . Oh and why switch from hypo to copper , if you can do it correctly its very effective and easy on your fish , some fish don't do well with copper .