What test kit are you using? Your first post is confusing me. You said there is no ammonia yet somehow suspect if the ammonia is increasing after you overfeed. If you have issues with your cories not getting enough food, temporarily place a divider to separate the cories during meal time. Overfeeding is not an excuse to allow equal share among all your fish. It simply promotes overproduction of food leftovers and wastes, and deteriorates water quality even more rapidly.
Please test nitrate and nitrate.
Please test nitrate and nitrate.
