The only thing to do to lower cya is to do a partial drain and refill. Or you can just run higher than normal chlorine levels. See the best guess chart (which is actually factual and not a guess) in my signature line below. Also, cal-hypo isn't going to clear the pool any faster than bleach will. But, it will raise your calcium hardness reading. You are still ok at 200 but calcium is not needed in a vinyl pool --- no matter what the pool store tells you.