I am asking for your help. I have a cycled 29 gallon planted fish tank, I just put 2 platy's, 1 small potbelly molly, and 1 small algea eater in it a week ago that came from my 10 gallon tank. The 10 gallons water was nearly identical to the 29 when put the fish in it. Both Platy's now have been at the surface in the back corner away from the filter and heater. They are not gasping for air but their mouths are right at the surface all day long. They do not move swim down but then quickly go back to the surface. They do still eat. But my water temperature is at 78 and i have a filter that is for a 40 gallon tank, Ammonia is at 0, the nitrites are at 0 the nitrates are between 10 and 20 ppm. I use the API freshwater test kit. I'm working on getting the ph down from 8.5 to 7.5 with drift wood. I have an air pump that is made for a 10 gallon tank with a 5 inch airstone. I am wondering if this is happening because the PH levels are too high or is it that the air pump is too small or something else?