CyclingAquarium Nitrogen Cycle: How to Build a BiofilterThe aquarium nitrogen cycle is the microbial conversion of toxic ammonia into nitrite and then nitrate. A tank is ready only after its biofilter repeatedly…Cycling
Aquarium Cycling: Build and Verify a Working Biofilter
Establish biological filtration and prove that it can process the intended waste load.
Cycling grows attached microbial communities that convert ammonia to nitrite and then nitrate. A calendar cannot confirm readiness, so these guides focus on controlled inputs, repeatable testing, oxygenated media, and the evidence needed before animals rely on the biofilter.

Featured guideAquarium Nitrogen Cycle: How to Build a BiofilterOpen guide
Your learning path
Build the skill in the right order
Featured content
Aquarium Cycling guides
CyclingAquarium Nitrogen Cycle: How to Build a BiofilterThe aquarium nitrogen cycle is the microbial conversion of toxic ammonia into nitrite and then nitrate. A tank is ready only after its biofilter repeatedly…Helpful resources
