I have a 36 gallon aquarium with an Aqueon power filter 30 (200gph). I just completed the fish-in cycle a week ago using 2 zebra danios (new to aquariums and did not know about fishless unfortunately). The cycling took about 7 weeks. My ammonia lvls spiked then settled to zero, nitrites spiked and settled at zero. I tested 4 days straight and got zero for ammonia and nitrite. I had around 20 ppm nitrate. I added 4 zebra danios to my tank after that and everyday since then I have been getting a trace of ammonia (below .25). Is that normal? I havent done a water change yet and the ammonia lvls havent risen any higher than that.