If the tank is 4 months old it's cycled by now. Just don't replace your filter media. You may want to swish it in old tank water during water changes to remove any waste/food/etc particles that have built up and may be getting back into your water. Also what's your water change schedule/frequency? A regular weekly water change schedule of 50% with a substrate vacuum should keep things pretty clean; it may be as simple as upping your cleaning frequency. What do the white particles look like? Do you have micro bubbles from your filter or an air stone, that can make water look cloudy as well.
And BB lives on all filter media, including filter pads, sponges, etc., not just ceramic media.