I have a 10 gallon aquarium with 2 common goldfish. This tank went through a fishless cycle about 3 months ago, the parameters were: 0ppm ammonia 0ppm nitrite 10ppm nitrate i did a gravel vac and a 50% water change 3 days ago, however my water parameters just suddenly went out of wack. idk why: .25ppm ammonia 0ppm nitrite 10ppm nitrate i know that's not bad, but that .25ppm ammonia concerns me. i'd expect ammonia to pop up after a week of no cleaning, but it's only been 3 days... whats wrong? is this ammonia caused by something gone wrong with my beneficial bacteria, or because goldfish just produce a lot of waste? also, is .25ppm ammonia harmful to my fish to any extent? P.S., i realize 10 gallons is too small for my goldies. i'm currently (fishless) cycling my 75 gallon tank and they should be moved by the end of the month hopefully.. P.P.S. when i said "This tank went through a fishless cycle about 3 months ago", i meant that it was fully cycled 3 months ago, and my goldies have been in it since then. the tank did not take 3 months to cycle. just some clarification.