Hi. I have sifted through the entire tank and found nothing on multiple occasions, snd I check my filter every three weeks just to make sure there isn’t any gunk in it. I do not wash it out. When I do the water changes, the ammonia is immediately at 2ppm still. It makes no sense. Even with a 100 percent water change, I STILL had 2ppm ammonia one minute after refilling was complete. Great source water