alright, i did a 25% water change yesterday. before the change the levels where 0 ammonia, 0 nitrite and 20 nitrate. Now, a day after the change it's now .50 ammonia, 0 nitrite, and 10 nitrate. i am using RO water. Why is my ammonia level up? should i be worried? any suggestions would be helpful as to what caused the levels to rise. what can i do to keep that from happening again.