The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.
As long as your not overpowering the tank with water current. Read up on your fish and see what kind of water they live in, in the wild, if their slow current fish it may not be the best idea, if their fast current fish should be ok.
If I where you, live plants are very, very good waste filters, also adding oxygen to your tank, you can get some really cheap plants like the hardy anarcharis( not sure I spelled that right) for about 3 bucks for about 5 stems, grow quickly, but I have to ask, what type of fish do you have in the tank?
I added my sponge filter yesterday, I also added some driftwood I boiled it a 3 or 4 times and removed all the tannins. 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?
Definitely do a water change!
The sponge filter will only add to your bio filtration capacity, if the levels have risen you must have changed something else.