By Stacey Blood
Director Of Operations
Blue Shark Trading Company

So you want to cycle a new aquarium!  This is, no doubt, hobbyist’s least understood step in aquarium keeping. It promotes more questions, confusion, frustration, and giving up than any other. But Blue Shark views cycling differently. We actually think it is fun! Why? Because it is more simple than many like to make it seem. Cycling, be it the long way or instantly, is systematic and has certain rules and parameters that provide a logical check list on how to get a cycle established every time. At Blue Shark, aquarium cycling is an extremely important step of custom installations. So what is aquarium cycling? It goes like this:

What Is “Cycling”?

The term “cycling” is defined by establishing biological filtration in the aquarium. Biological filtration, or the “biofilter”, is made up of bacteria that filter out the toxic ammonia from the aquarium via a process called “nitrification”. Nitrification is a two-bacteria strain process that turns toxic ammonia ultimately to nitrate. One bacteria serves as an “ammonia converter” that turns ammonia to nitrite. The other strain serves as the “nitrite converter” that turns the nitrite into nitrate, the end of the process. What we will do for the sake of this article is encourage you to think less of bacteria in terms of “microbes”, and more in terms of “livestock.  They have their own requirements, conditions, and care that must be practiced just like the live stock you can see.

Where Do They Come From?

Nitrifying bacteria don’t just “happen” in the aquarium, or in other words, just appear immaculately. Like everything else in your aquarium they must be imported from somewhere else into a new aquarium, even if it’s just a handful. They can be imported from media or objects from another system but most often they arrive in or on the fish themselves if media isn’t used. In order to start this colony of livestock, only one of each strain is required: One ammonia converter and one nitrite converter.

Let’s just say that in a system cycled only by introducing starter fish, one of each bacteria fall off and stick on some new media in the system. Starting with a population of 2 and with a division rate of once every 24 hours, with proper conditions and adequate food, nitrifying bacteria will grow to a population of 549,755,813,888 by the end of 40 days! With a flourishing colony your ammonia and nitrite will be at or around 0ppm with present nitrates and your aquarium is cycled.

The faster, and no less effective cycle, is to directly import nitrifying bacteria with a product such as Blue Shark Colony. While importing media from another system can establish biofiltration, using a biological proudct such as Colony works just as good and usually better because you know you have the amount of nitrifying bacteria needed in every bottle. Such information isn’t provided on a chunk of live rock. Colony also carries zero risk of transmitting any harmful viruses or pathogens that could be residing in other systems. Colony introduces millions of real, living nitrifying bacteria that gets the cycle done fast. The other benefit of this method is that you become aware of any possible water chemistry issues that could be hampering the performance and growth of nitrifying bacteria. It’s better to find this out in the first few days than 4-5 weeks later!

Sally’s Aquarium Cycled But Jim’s Didn’t. Why?

Water conditions. Before you start to cycling your aquarium it is important to go into it with some knowledge about how nitrifying bacteria live and survive. Think of your aquarium as a “power plant” for your bacteria and each individual water “parameter” as a toggle switch. As each condition is met, you flip the switch and the green light glows. When all of your switches are glowing green, your bacteria are powered and will function. Just one red switch and frustration likely follows. Just like you need a certain amount of oxygen, nutrients, water, and minerals to survive so do nitrifying bacteria. So what are these “parameters”?

Water: The Nitrification Powerplant

Before beginning your aquarium cycle, let’s look at the aquarium as something different like, say, a power plant and a light bulb. The water plays the part of the power plant and the nitrifying bacteria plays the part of the light bulb. In an aquarium the nitrifying bacteria is just as dependent upon the water conditions as the light bulb is upon the power plant. No juice? No go. Below are the water conditions, or toggle switches, that must get a green light before the power plant will work and the light bulb will turn on with maximum brightness!


Nitrifying bacteria are waterborne, aerobic microbes. This means they require oxygen to function properly, but not necessarily to live (more on this later). A properly aerated system with plenty of oxygen is necessary for a quality cycle. The less oxygen they have, the more lethargic they get and require less feeding, which results in less ammonia and nitrite being consumed in the system. The more oxygen, the better. If your aquarium is properly aerated, then you have your first green light!
Temperature is very important to nitrifying bacteria. Varying temperatures bring about different results on the high and low end. Nitrifying bacteria will live between 32°F-112°F. Outside of that range they will die. This means that nitrifying bacteria cannot be frozen! This also eliminates the possibility of nitrifying bacteria arriving in powder or spore form. The optimum temperature for nitrifying bacteria in an aquarium system is between 74°F-86°F. Falling below 74°F will result in slower metabolism and conversion will occur much slower, being cut in half at around 65°F. If your temperature is within the optimum range then you have another green light!
pH is very important to nitrifying bacteria as well. In most freshwater systems it is recommended to maintain a pH of between 7.4-8.0 and 8.0-8.3 in most marine systems. pH outside of that range will stress the nitrifying bacteria and a drop-off in production is likely to result in most cases. Flip that switch and get yourself another green light!
Alkalinity is usually the integer that gets lost in starting an aquarium. It is rarely checked in this context and it’s the most frequent cause of cycling frustrations. Alkalinity generally isn’t a problem with marine aquariums due to the added salt containing most of what nitrifiers need. Alkalinity is, by far, most problematic in freshwater systems. As *tap water is most definitely recommended for freshwater aquariums instead of R/O water stripped of necessary trace elements and phosphate, it is different depending on where you live. Total alkalinity carbonate hardness (KH) should be kept at no lower than 70 KH (7 dKH) and recommended between 90-120 KH (9-12 dKH) minimum. This should be checked or verified before attempting to cycle your freshwater system. Another green light!
Phosphate?? What??? Phosphate is one of the fundamental building blocks of life on Earth. Therefore, if nitrifying bacteria is deprived of phosphate they will not function. This is a problem when **R/O or DI water is used instead of tap water. Water that has been intensely filtered will be void of not only phosphate but other necessary trace elements, notably calcium, magnesium, and sodium bicarbonates. In some very, very, very rare cases water like this can come out of the tap in urban areas from rural areas. This is why it is important to check total alkalinity and even phosphate if possible if you are in one of these areas.

Let’s Go LIve!

*hum… spark… spark…..* We’re live!  With an introduction of an ammonia source your nitrifying bacteria now have a place to live, grow, and give you years of joy with a healthy aquarium!

  • * Tap water is recommended for freshwater systems due to the fact it typically contains the necessary amounts of phosphate and trace elements for nitrifying bacteria growth.
  • ** If R/O water is used in a new freshwater aquarium it is recommended to supplement it with trace elements and a source of phosphoric acid to “age” it.


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