Diagram of the <a href="https://en.wikipedia.org/wiki/nitrogen_cycle" class="extiw" title="en:nitrogen cycle">nitrogen cycle</a> in an <a href="https://en.wikipedia.org/wiki/aquarium" class="extiw" title="en:aquarium">aquarium</a>.  Drawn by <a href="https://en.wikipedia.org/wiki/User:XcepticZP" class="extiw" title="en:User:XcepticZP">XcepticZP</a> original available at [Image:Aquarium_Nitrogen_Cycle.png].
Users <a href="https://en.wikipedia.org/wiki/User:XcepticZP" class="extiw" title="en:User:XcepticZP">XcepticZP</a>
2007-07-12
<span class="int-own-work" lang="en">Own work</span>