i have had my tank up running and cycled for about 3 months i do 20 percent weekly water changes and test my water weekly . today i tested my water and had 0 amonia 5 ppm nitrite and 20 ppm nitrate. this has never happened before. after a 30 percaent water change amonia stayed at 0 nitarte dropped to 2 ppm and nitrate dropped to 10 ppm what should i do now as this is so high any ideas what caused this .? by the way when i do my water changes i use a gravel cleaner to change the water so it sucks up all the crud. please help what to do now?