it seems like everytime I do a water change my fish go in distress. I did a 50% last night and now all my fish are at the top gasping. I use Amquel plus as a water conditioner. Do you think that may have something to do with it? Any help on this is much appreciated. One of JDs is laying on the floor of the tank so this is not good. I checked my Nitrate which is now 5.0,Amonia is .25, PH is at 7.0. and Nitrite is .50.