Put in an order with Jimbo on the upcoming bulk reef order, check out the thread on it, there is a refractometer for under $40. You won't regret getting it.
This is definitely the way to go. Refractometers can be calibrated using DI water. Then you know you are getting the right salinity reading. Much quicker to use as well, just a couple drops of water on the viewing area and you are ready to check. Also, I'm assuming you mean you keep your salinity a 1.021 not 0.021 right?