Chapter 5: The Nitrogen Cycle

     So when do I get to throw some fish into my tank? Well, hold on there, partner! There's an absolutely crucial process that has to take place before your tank is anywhere near ready for livestock. You mean I put all this money into my tank, filled it up with water, and now I have to wait even longer? If you'd like to save some money and some fishy lives, I'd highly suggest so.

So what is this so-called "Nitrogen Cycle"?

     The Nitrogen Cycle or simply put, the "cycling" process of your new aquarium, refers to an ecosystem exchange. I'll try to explain how simple it all is in a few easy steps. 

  1. It all starts with ammonia. Ammonia can be produced a number of ways in a new tank without risking the lives of live fish.
  2. In turn, Ammonia is consumed by nitrite, which is a by-product of bacteria.
  3. At this point, nitrite is consumed by the by-product of bacteria known as nitrate.
  4. Okay, okay, so what consumes nitrates? Live plants definitely help, which is why it is great to have a refugium, but water changes are one of the easiest ways to lower your nitrates. Nitrates are also consumed by algae, but that's why we add macro algae to our refugium to out-compete nuisance micro algae that can take over your display tank.
  5. Lastly, our algae and plant growth that results from consumption of nitrates provides an excellent food source for our tank's inhabitants.

Here's just a few ways to get that cycle started!

  • Live Rock and Live Sand are some of the most beneficial additions to a new aquarium! If you can afford it, it's full of thriving bacteria! Your LFS is usually your best bet to adding it in time.
  • Bottled Bacteria is a great start as well. You can usually pick this up at your LFS and some pet stores.
  • Consider using a piece of filtration from an already-matured reef tank. My LFS loves to help people out with donating pieces of their filtration system.
  • Adding Pre-Cycled Water can also be a huge help! If you can snag some water from an up and running system, this will greatly expedite the process.

     In a nut shell, bacteria is the key! And that all starts with the time it takes for your bacteria to populate your filtration. While high levels of nitrite and ammonia can be very dangerous for your livestock, it's crucial to wait out the Nitrogen Cycle for your healthy bacteria to balance it all out! Some say it takes a couple of weeks to overcome the new-tank syndrome, others say it can take a couple of months to fully develop. Just be patient, and monitor your water parameters a couple of times a week. You can usually have your water parameters tested at your LFS for a very small price. 

Here are some general guidelines to see how your tank will cycle and also know when it's done!

I love this illustration from

I love this illustration from

     As a good rule of thumb, it would be a good idea to do your first water change just as soon as your cycle has come to an end. At this point your nitrates are probably going to be extremely high, while your nitrites and ammonia are almost non-existent.

     On a side note, the first few weeks before the addition of any livestock might be a great time for you to invest in a good test kit to test your essential water parameters like nitrites, nitrates, ammonia, and salinity. For salinity, I'd suggest spending the money on a quality refractometer. Even though this might all seem like some huge expenses up front, they'll greatly attribute to the success of your reef tank in the long haul! t's all just a circle of life, right? And it ain't so hard to understand!

     Have you had any success in expediting the nitrogen cycle? We'd love to hear your thoughts. Feel free to comment and like this article below!