pH was 7.8 when you added the cal hypo. How high was your TA and calcium hardness at the time? High TA, elevated pH and high calcium can cause oversaturation of the calcium in the water with the addition of more calcium (cal hypo) and cause calcium carbonate to precipitate out and cloud the water. Dropping the pH to around 7.2 can help clear the water by causing the calcium carbonate to redissolve but we really need a full set of test results to know what is going on.