Everyone above is essentially correct. I havenít purchased bio media in sometime and the only two tanks of mine that use it use it because it came with it and my other hang on backs use a coarse sponge prefilter and filter floss inside (these are the cartridge hobs). All my other tanks use under gravel filters. I really think of filters now as just water movers. Most planted tanks that are doing ok have more than enough surface area in the substrate and combined with plant growth handle all forms of ammonia. Of course if your tank is super stocked with little to no plants and minimal water changes and minimal substrate then yes an appropriate filter will benefit you. As far as what you fill it with it really doesnít matter, sponge, ceramic/plastic media. LRB Aquatics runs 250 tanks all filterless and just uses the principals I spoke of and manages everything via water changes.
Sent from my iPhone using Tapatalk