Getting a new turtle tank can be exciting. I have been there; you can wait to introduce your turtle to its clean and fresh habitat. But then you must have heard many recommend properly cycling your tank. And so a curious you ask, “why must turtle tanks be cycled?”

Turtle tanks need to be cycled to enhance the development of beneficial bacteria in the turtle tank. This is important to reduce the toxicity of the water, ensuring your turtle can enjoy smell-free, cleaner, and fresher tanks. Upon appropriately cycling your turtle tank, the nitrite, nitrate, and ammonium content emanating from the decomposition of unconsumed food and turtle waste is shrunk to the barest minimum.

To better understand the importance of cycling your turtle tank, we have to examine the nitrogen cycle and how it works in a turtle tank.

What Really Is A Nitrogen Cycle As It Relates To Your Turtle Tank?

The conduciveness of aquatic environments – typical of your tank – for your turtle depends on how appropriately the nitrogen cycle is managed. 

The nitrogen cycle controls the development of helpful bacteria in the tank saddled with the responsibility of eliminating the toxic nitrogenous waste your turtle releases. 

Such nitrogenous waste can be in your turtle’s feces or result from the decomposition of the uneaten food you dish your turtle. This decomposition releases a significant amount of ammonium into the turtle tank. 

High ammonium levels are toxic for your turtle. With a properly managed nitrogen cycle, such elevated ammonium levels can be reduced by growing colonies of beneficial bacteria. 

These bacteria break down the ammonia into nitrate (from nitrite). Nitrosomonas marina is one of the most notable helpful bacteria that break down ammonium. This bacteria is reputed for its capacity to digest ammonia, transforming it into nitrite.

These bacteria could be combined with other Nitrospira and Nitrobacter bacteria species to further convert the nitrite (produced by Nitrosomonas marina) into far-less nitrate. 

Should you have plants integrated into your turtle tank, they can “eat up” the nitrate content, leaving you with significantly fresher aquatic surroundings for your turtle. 

Compared to ammonia, nitrate is far less toxic, and periodically changing your turtle tank’s water can keep the nitrate content at optimal levels. 

If the nitrogen cycle of your turtle’s tank water is not appropriately maintained, you would need to change the entire water content of your tank at least once every seven days to prevent the ammonium from accumulating to toxic levels. However, if you were adequately managing your nitrogen level, changing just one-quarter of the water content would do.

Can You Use Feeder Fish To Cycle Your Tank?

In the past, fishes were famously deployed in turtle tank cycling. This aims to trigger the conversion of ammonium to nitrate by introducing a handful of feeder fish into the turtle tank.

This was done in the expectation that the waste from this maiden set of tank inhabitants (herein the fish) would enhance the cultivation of helpful bacteria. 

However, such feeder fish struggle to cope with amplified ammonia (and nitrite) levels, often getting ill or outrightly dying from the substantial toxicity of the water. 

So, how do you properly cycle a turtle tank?

Yes, the days of cycling turtle tanks with feeder fish are far gone, but how do you get the cycling process started then?

First things first, we need water in your tank. The standard rule is the water volume should be at least five times the width and length of your turtle.

With your tank filled with water, you can either introduce naturally homemade ammonia (not ammonia-containing cleaning agents) or just turtle food into the tank. For the quantity, two drops would do for two 7.5 liters of water.

The water chemistry would now determine the next step. Within the next 48 hours, you should see reasonable hikes in ammonium levels. If this doesn’t occur, you need to add more ammonium or turtle food and wait a bit more. 

If a jump in ammonium occurs, you would need to ramp up your tank water monitoring to a daily routine (to ascertain the development of the chemical process), consequently adding more ammonia and turtle food. 

The ultimate objective here is attaining ammonium content levels anywhere between three to five parts per million (ppm).

A corresponding increase should follow this in nitrite levels. By now, it is more apparent that a colony of helpful bacteria has been successfully established and is beginning to process such ammonium to nitrite.

Should this be succeeded by substantial increases in nitrate (with a corresponding decline in ammonium and nitrate levels), then you have done an excellent job in cycling your turtle tank. But then, how do you know you have finished the turtle tank cycling?

Tell-tale Signals Of A Successfully Concluded Turtle Tank Cycle?

Your turtle tank only becomes fully cycled if it can reduce the ammonium content almost independently (without you fully changing the water or having to introduce more ammonia frequently).

When cycled, your turtle tank’s nitrite levels should be almost zero (or around 0.5ppm). The same applies to ammonium levels. For the nitrate content of a properly cycled turtle tank, this shouldn’t exceed 40ppm. The chlorine level should be absolutely zero.

To make the aquatic conditions of the turtle tank simultaneously conducive for your turtle and your helpful bacteria, the PH level of your turtle tank should oscillate between 6-8.

If you have more than turtles in the tank – say you have other living organisms cohabiting the tank with your turtles – then you have to factor them in when deciding the optimal water chemistry of your tanks. Take note that the likes of crustaceans and fishes are more quickly affected by negative chemical substances in your tank than your turtle.  

What To Bear In Mind About This Cycling Procedure?

The said procedure requires a bit of diligence on your part, especially when you wish to introduce your turtle into the tank before completing the cycling process. 

The reality is that it would take anywhere from weeks to months before a substantial colony of helpful bacteria to be cultivated in your turtle tank. 

During this process of cultivating and stabilizing the bacteria population, your ammonium and nitrite levels, as said, would significantly increase. So if you have your turtle inside the tank by this period, you have to check the water chemistry very frequently – preferably multiple times a day.

Should you notice significant leaps in nitrate and ammonium levels before the bacteria are fully established, you have to dispose of a quarter of your tank water and introduce fresh water in its place. If the ammonium levels were really high, just replace half of the water content.

Such introduction of fresher water would lower the concentration of ammonium and other potentially toxic chemicals in your turtle tank. Until the toxicity of the tank reduces, you must replace the water several times a day as the inhabitant turtle would always add ammonium to the water. 

How Long Does Cycling Take?

The farthest a turtle tank has taken me is two months. There are times where I could successfully cultivate and stabilize the beneficial bacteria population (and consequently reducing the ammonium, chlorine, and nitrite levels to zero) within six weeks. 

Yes, you can “artificially” accelerate the pace of cycling. One popular means is borrowing bacteria from a tank you have successfully cycled before. This is achievable by transferring used filter media from an already-established tank into the one you are cycling.

The type of water you are borrowing the bacteria from must rhyme with the type of water of the tank you are introducing it to. Take, for example, bacteria lifted from an already-established saltwater aquarium will not thrive if introduced to a turtle tank containing fresh water.

The said bacteria transfer must be executed with minimal delay. If you remove bacteria from a tank intending to introduce it to a new tank, make sure the bacteria is aerated within 15 minutes at most. 

Some breeders leverage commercial bacteria supplement to speed up the progression of their tank cycling. These bacteria starters are typically adapted for fish and turtle tanks.

Bear in mind that these bacteria supplements do expire after the exhaustion of their shelf lives. Therefore, it would be unwise to pick pond bacteria when you have insufficient habitats to deploy before such supplement’s shelf life is exhausted.

Can You Use UV Sterilizers During Cycling?

Commonly, I get asked about how appropriate it is to use UV sterilizers when cycling turtle tanks. UV sterilizers should only be deployed in your turtle tank (to eliminate algae) when you have fully cycled it, and the colony of helpful bacteria is well established.

If the UV sterilizers are used in cycling, especially when the colony is yet to be established, there is a notable risk of killing the friendly bacteria.

Resources

https://www.hitchcockcenter.org/blog/cycling-the-painted-turtle-aquarium/
https://nmlc.org/2011/06/the-critter-tank-and-the-nitrogen-cycle/
https://users.cs.duke.edu/~narten/faq/cycling.html
https://www.thesprucepets.com/keeping-water-in-your-turtle-tank-clean-1238362
https://www.buildyouraquarium.com/turtle-tank-setup/