Hey all, I'm a fairly novice fishkeeper, so please go easy on me
I have set up a small 2.5 gallon tank for one of my Betta fish with a small Red Sea Nano HOB filter. I am in the process of just letting it run for a while before putting him in there. After a couple days the water started to smell funny so I checked the ammonia and it was at 1ppm (still no fish in the water yet). I did a 50% water change to see what happened. Couple days later ammonia was back up to around 1ppm. I suspect the rock I have in there is causing this because it came from another tank. Perhaps fish slime and/or waste stuck in the pores of the rock? And yes, I cleaned the rock, gravel, and plant very thoroughly before adding them to the tank. Not sure if i'm missing anything or what I can do other than throw out the suspect rock, lol.
Oh for the record, I am familiar with the Nitrogen cycle. I have already cycled other tanks and have a very happy healthy betta in a cycled 5 gallon right now.