Topping off with the 1.032 water is fine, but without a refractometer to test it, it may not be accurate. I went almost 9 years using a hydrometer, then got a refractometer and it was off. Mine was too high, so I now understand why others always told me to get one. Mine is just a $30 one from Premium Aquatics and it works great. Just be sure to get 1.026 calibration fluid.