PH could be an issue but only if the fish are used to a lower PH. Ours here on FL are in 8.4 and higher PH. PH issues come from it dropping more than it being too high. My concern is the ammonia. In an established tank, ammonia should be 0 and rises in it shouldn't be long enough for you to get them to register on a test. So, were these pics taken before the water change and has there been any difference since the water change?