Ok. I have a 45 gal tank with discus and clown loaches. Ammonia and nitrites have been at 0 and nitrates at 10. I did a W/C yesterday. I woke up this morning and found the discus looking stressed. The clown loaches seemed normal. I dunno what kinda happy pill they took. I broke out the water tests and found out the ammonia and the nitrite was at .25 & 1.0 respectively!!! I tested the water again. Same $%&@. I tested the tap. No problem there. The last place I tested was the water aging trashcan. There was the problem. Same readings. After nearly breaking my back changing water with the good old 5 gal bucket, I hope I saved all my fishes. Has this happened to anybody? Can anybody explain why there was ammonia and nitrite in my water barrel? I really loved changing water with the water pump too. 