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Week 17: How To Cycle a Saltwater Aquarium!

Updated 2023

Regrettably, the process isn’t complete simply because we’ve filled the aquarium and arranged our equipment. Before introducing fish and corals, every new saltwater aquarium must undergo what’s known as the “nitrogen cycle.” There exist several approaches to facilitate this cycle, with potential for acceleration, yet an average waiting period of approximately 3 weeks should be anticipated for its completion. In this week’s content, we’ll delve into various tips, as well as things to avoid, offering insights on navigating this crucial phase.

This Week's Video:

What Is Cycling?

Let’s not dive too deeply into the intricacies of biology and ecology, but it’s important to recognize that every natural aquatic ecosystem thrives on a multitude of bacteria that consume the toxic waste produced by larger organisms. However, in a new aquarium, the initial challenge lies in establishing a robust population of these beneficial bacteria. Failure to do so can result in a rocky start for your aquarium. Ensuring the ongoing health of these bacteria is equally critical, but that’s a topic for another discussion.

Typically, the cycling process spans about a month. However, this timeline can be influenced by the usage of certain products, potentially shortening or extending the cycle. Providing ample surface area for bacterial growth is beneficial, achieved through elements like sand, porous rock, and bio-media. To gauge the progress of your cycle, regular testing of ammonia, nitrate, and nitrite levels is essential.

The cycle is considered “complete” when ammonia and nitrites are at low levels, and nitrates fall within the range of 0 to 40 ppm.

Three Ways to Cycle An Aquarium

Approach One (Dead Shrimp Technique)

The traditional approach involves acquiring a piece of deceased shrimp, preferably a larger one, and placing it within your aquarium. The shrimp serves as both a source of food and as a potential carrier of ocean-borne bacteria. To prevent decomposition, it’s wise to enclose the shrimp in a net or a glass container. While this method is straightforward, it’s not exceptionally rapid and does come with an odor.

Approach Two (Live Fish)

This method is somewhat contentious due to its potential impact on fish welfare. Essentially, it entails using robust fish species capable of enduring elevated levels of toxic compounds. These fish are then fed normally, providing sustenance for the developing bacteria. While it can expedite the cycling process, it often results in fish casualties. Additionally, even if the fish survive, they might not align with your intended aquarium inhabitants, necessitating their rehoming.

Approach Three (Fishless)

The most scientifically inclined technique involves the use of ammonia paired with bottled bacteria. Numerous companies offer products with user-friendly instructions for this purpose. This approach is likely the swiftest and least distressing for living beings involved.

Things To Know During The Cycle

Stay vigilant about testing your water regularly to track the progress of the cycle and determine when it is genuinely complete.

Remember the following precautions during the cycle:

  • Avoid activating your lights
  • Perform water top-offs, but refrain from water changes
  • Keep your protein skimmer (if present) turned off
  • Deactivate your UV Sterilizer (if present)
  • Abstain from using filter socks

Even after successfully completing the initial cycle and introducing your fish, be prepared for the possibility of a secondary cycle. Additionally, don’t be alarmed by the emergence of an unsightly phase marked by the appearance of brown accumulations known as diatoms. This phenomenon is normal and an integral part of the natural progression.