Sudden Alkalinity Drop

what is your PH at as low Ph is hard on those flashers and many other fish in general. It can also cause the Zoos to close up. I would get a new test kit and take a sample with pipit from the middle of the water column or center of tank water tends to be in motion there more consistently and you get a better reading. Its kind of like when you do a test on a pool you are suppose to take the sample from a bout 2-3 feet below the surface and around the middle of the pool to get the most accurate test results.

Bill