I've found that 1.5 to 2 degrees works well. An additional comment for you to consider as you add floats to your plane...Have the CG correct for the plane as it is flown on wheels. Then, when setting up for floats, in establishing the CG of the plane on floats do so by adding weigh to the floats, not to the plane. In this way you are always assured of the correct CG no matter which configuration you are flying and don't have to worry about adding weight when changing, etc.