Hey guys just came in today, i dont work the weekends. After testing his tank, its a 55 gallon, i got came away with the following results. PH was very low around 6.0, the ammonia was up around 1.0 PPM and i had no trace of nitrite or nitrate. I had tested the water a week ago and came out with no tracable amount of ammonia, nitrite or nitrate. The tank has a fluval 404 and a whisper 100 air pump. I had cleaned the filter last week and gave the tank about a 10% water change. He currently inhabits the tank with about a dozen and a half bloodfin tetras and another dozen or so assorted tetra, bleeding heart and lemon i believe are the only others.
What would cause that drop in PH and the rise in ammonia? The ray was eating last week but is not today when i offered food. The ray is about 4" not including tail.