I have a ten gallon tank that has been cycled for months. I am using a whisper filter. Recently I had to change the filter pad because it just fell apart when I pulled it up to check it. I have been trying to just rinse it in aquarium water and replace. Well I bought an Aqua Clear Fluval Filter for th 10 gal and set it up next to the whisper filter to let it run and gather bacteria, well checked my parameters today and I have a slight Nitrite problem. I changed 10% of water, vacuumed, added, safe start and easy balance plus. I took out the Fluval filter for now. Any advice for me?