Hi guys. So I know about fishless cycling but my question lies in fish in cycling...kinda. So I have a tank that used to have fish in it but after having a few fish die...old tank syndrome or disease....I let the tank sit with no fish for a while. Anyway, I did several complete or near complete water changes then decided to start stocking. The tank is 75g by the way. So the fish in there now are 3 cories and 5 guppies. Every day I test for ammonia and end up doing a large (50-75%) water change. Every day I test it it looks to have between 2-4 ppm ammonia only 24 hours after the water change. Before starting to stock this tank I did a good clean out of the dirty filter so Im assuming the ammonia isn't from there. The only thing I didn't clean out is the fake rock decorations that are hollow but open so water/debris can get in them. I really doubt that few fish is making that much ammonia daily. What do you think? Is the ammonia from the fish or dirty inside of the decorations?