Fishless Cycling - Disadvantages

Disadvantages

• Phosphates are often created as byproducts when decaying fish food is the source of ammonia.
• There might not be enough ammonia to allow a sufficient population of bacteria to colonize when fish food is the source of ammonia.

Note that these are not problems when ammonium hydroxide or ammonium chloride is used as the source of ammonia.

• It might cost more than using a few cheap fish to cycle the tank, if you include all the cost of the water test kit, pure ammonia, etc.

• Pure ammonia cycling is not as quick nor does it allow as higher bio load stocking of the aged filter media method.