If you use reliable media and enough of if you will be fine. I just got 2 very used sponge filters and set them right under my canister filter pickup and the other under my hob pickup. I added all of my fish all at once to make a full load to keep the bacteria alive in the sponges. I had water cycling in the tank for about 36hrs with dechlorinates before adding sponges or fish. Nothing EVER spiked and my first water change was 2 weeks later because I had almost 10ppm nitrates. Now into a weekly routine of about 40-50% w/c. Im on my 5th week. I didnt believe the guy who told me to do this but he also guarenteed the fish he sold me so I just tried and it looks like he was right.
