Presently having problems with very low Ph levels in a 30 gallon tank. We have two Pacus running on an Eheim Classic and a DIY filter with a powerhead attached providing moderate aeration. Pacus are 17" and 12". Ph level always read 6.0 and possibly lower. We don't have anything else to test how much lower the Ph really is. Our nitrate, nitrite and ammonia are all fine. However, they still seem to be "gasping" at times. The fish will be moved to a larger tank (120 gallon) soon. Does anyone know what Ph levels Pacu live in? What is the best way to balance the Ph?