I have a couple month old 10 gal freshwater with 5 black skirt tetras, a couple ghost shrimp, and 2 java ferns. I have a Marineland filter with a biowheel. Yesterday I added added a sponge filter. I also added some driftwood I boiled it a 3 or 4 times and removed all the tannins for about 20 -30 minutes each. But when I tested my water, the nitrite (N02-) levels skyrocketed. They have always been at 0ppm and now they are right around 4 or 5 ppm. My Nitrate (N03-) levels are at 5 ppm and my Ammonia levels have come down since I have last tested it. Is the high Nitrite (N02-) and Nitrate (N03-) levels due to the sponge filter becoming established? Should I do a 20% water change?