I was just wondering what holds the most bb in a canister filter- coarse sponges, bio balls, ceramic rings, or matrix? I have cascade 1000s with three trays, how do you guys/ gals prefer to load them? I had a 29 gallon with a Sunsun that stated leaking. In it, I had a coarse sponge, a fine sponge, bio balls, and ceramic rings. About 3 weeks before starting a new 55 gallon tank, I added matrix. I moved the matrix to the new tank to seed it, then dosed it to 2 ppm ammonia. For 5 days, it sat at 2, 0, 5. Today I was happy to see .5 ammonia, somewhere between 2-5 nitrite, and 40 nitrate. Dosed back up to 2 ammonia, we'll see what we get tomorrow! So I'm assuming I have both bacteria, but they just need to catch up? Or am I in for several more weeks of waiting?