Turtle Tank Nitrogen Cycle – Complete Guide & Diagram

Understanding the nitrogen cycle is an important part of keeping the water clean and healthy in a turtle tank, but you don't have to be a chemistry nerd to understand how it all works. It's actually pretty straightforward!!
Turtle Tank Nitrogen Cycle
Turtle Tank Nitrogen Cycle

This turtle tank nitrogen cycle guide will cut out all the complicated stuff and explain it in simple easy to understand terms.

What Is The Nitrogen Cycle In A Turtle Tank?

The nitrogen cycle (also known as the nitrification cycle) is a process where naturally occurring nitrifying bacteria (beneficial bacteria) convert toxic substances in your aquarium water into a much less harmful substance.

It basically converts toxic water into safe water.

How and why this occurs is because turtles are just like us, what goes in one end must come out the other end!! When we’ve done “our thing”, we flush, and away it goes.

A turtle doesn’t have that option, they have to swim around in their own toilet. Their poop then starts to break down in the water and releases ammonia which is toxic.

On top of that, any food they missed during feeding, dead tankmates, or any dead plant matter trapped in the tank will start to rot and release ammonia.

The nitrogen cycle is nature’s way of dealing with it all.

However, in a new aquarium, there aren’t enough beneficial bacteria to get rid of these toxins quickly enough.

It takes time to establish these bacteria and stabilize the cycle.

Turtle Tank Nitrogen Cycle Stages

There are 3 stages to the turtle tank nitrogen cycle.

1 – Ammonia – NH3


Turtle poop, leftover food, and rotting vegetation begin to break down and release ammonia into the tank water.

2 – Nitrite – NO2


Once you have ammonia in your water, naturally occurring nitrifying bacteria called Nitrosomonas will begin multiplying on your aquarium’s surfaces.

These bacteria consume ammonia and convert it into nitrite.

Although nitrite is less toxic than ammonia, it’s still not good for turtles.

3 – Nitrate – NO3


Now you have nitrite in your water, there is another form of beneficial bacteria called Nitrobacter, that will consume nitrite and turn it into nitrate.

Nitrate is far less harmful, but it still needs to be kept at safe levels of <40ppm.

You keep the nitrate at safe levels by cleaning your aquarium and performing partial water changes when needed.

Turtle Tank Nitrogen Cycle Diagram

It may be easier to visualize with this turtle tank cycling chart diagram:

Turtle Tank Nitrogen Cycle Image
Turtle tank nitrogen cycle diagram

Do Turtles Need The Nitrogen Cycle?

Yes, they do as it helps remove toxins and odors from the tank water.

While turtles aren’t as sensitive to ammonia and nitrite as fish, it still isn’t good for them.

It’s a naturally occurring process that just needs a bit of time to establish itself.

How Do You Start A Nitrogen Cycle In A Turtle Tank?

Cycling a turtle tank is the same process as cycling a fish tank.

I have an in-depth post on how to cycle a fish tank that will guide you through the various options step by step.

Option 1 is by far the easiest, quickest, and best way to cycle a tank, so check it out if you want to cycle your tank FAST!

How Long Does It Take To Cycle A Turtle Tank?

The nitrogen cycle in a turtle tank takes anywhere from 2-8 weeks to complete.

It all depends on which method of cycling your tank you choose to use.

How Do You Maintain The Nitrogen Cycle In A Turtle Tank?

You can maintain the nitrogen cycle in a turtle tank by:

  • Equipping your turtle tank with a high-quality water filter
  • Not overstocking your tank
  • Not overfeeding your turtles
  • Removing any dead fish they may have snacked on
  • Removing any rotting plant matter
  • Testing your water regularly
  • Cleaning your turtle tank and performing a partial water change when Nitrates exceed 40ppm.
  • Increase your biological filtration if necessary

How Do I Increase My Biological Filtration?

If you need to increase your biological filtration in your turtle tank, one option is to add some biological filtration media to your filters, such as ceramic rings or bio balls.

These products increase the surface area for beneficial bacteria to grow on which will reduce the amount of ammonia, nitrite, and nitrate in your aquarium.

If you’re having difficulty keeping your nitrate levels under control, another option is to add some plants to your turtle tank, as they feed off the nitrates in your water.

Be aware, that if there aren’t enough nitrates in the water to feed the plants, they may die unless you fertilize them with something like API Leaf Zone.

Turtle Tank Nitrogen Cycle Summary

Here’s the turtle tank nitrogen cycle summarized in 5 sentences:

  1. Turtle poops in the water.
  2. Turtle poop and other organic matter rot and release ammonia.
  3. Beneficial bacteria grow and convert ammonia to nitrite.
  4. Another kind of beneficial bacteria converts nitrite to nitrate.
  5. You remove nitrates with water changes and plants.

Closing Thoughts On The Turtle Tank Nitrogen Cycle …

You now know how to cycle your turtle tank successfully.

Told you you don’t need to be a chemistry nerd to understand it! 🤓

If you keep your nitrogen cycle balanced, you’ll have a thriving aquarium with a happy and healthy turtle.

Should your turtle become sick you can find your local turtle vet here.

Check out the turtle section for more in-depth guides and product reviews and the aquarium health section for guides on keeping your aquarium in tip-top shape.

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Hey, fellow fish enthusiast 👋! I'm Paul and I've been an aquarium addict since I won my first goldfish at the fair many years ago. Let me share with you the knowledge that I've gained along the way (and avoid the mistakes I've made!), so you too can create an underwater paradise for your aquatic friends.