Randy Holmes-Farley uppmanar akvarister att ta bort filter för att sänka nitrathalten i karen: 5. Remove existing filters designed to facilitate the nitrogen cycle. Such filters do a fine job of processing ammonia to nitrite to nitrate, but do nothing with the nitrate. It is often non-intuitive to many aquarists, but removing such a filter altogether may actually help reduce nitrate. So slowly removing them and allowing more of the nitrogen processing to take place on and in the live rock and sand can be beneficial. It is not that any less nitrate is produced when such a filter is removed, it is a question of what happens to the nitrate after it is produced. When it is produced on the surface of media such as bioballs, it mixes into the entire water column, and then has to find its way, by diffusion, to the places where it may be reduced (inside of live rock and sand, for instance). If it is produced on the surface of live rock or sand, then the local concentration of nitrate is higher there than in the first case above, and it is more likely to diffuse into the rock and sand to be reduced to N2. Det låter ju logiskt när man läser förklaringen. Så det blir att först ta bort det biologiska filtret (skitigast). Vänta någon vecka och sen ta bort det mekaniska filtret (bägge ser i princip likadana ut). Nitratdelen av filtret får vara intakt. Kan komma lite mer skit i slangen och ventilen till nitratfiltret men man får väl hålla lite koll så att det inte blir stopp eller för lite flöde (får jag ialla fall göra dagligen).