Cycling a fish tank

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Cycling a fish tank.

Thought I’d add a simple post about why you cycle your fish tank and why it’s important to do it before adding any fish into the tank.

I’ll try and explain each step in the simplest way so it helps people grasp the concept and why you do each stage.

When a fish is in the tank their uneaten food and pee and poop produces ammonia. Ammonia is toxic to them. There are other things like decaying plants that can cause ammonia but the main thing we’ll focus on today is waste from uneaten food and poop.

So now that we know a fish creates waste that causes ammonia to build up this leads us to why we add ammonia to cycle a tank. We are basically mimicking what will happen when a fish is in there. Because ammonia is toxic to fish we really don’t want a fish having to suffer unnecessarily when we can complete the process with no stress or harm coming to them.

There are various methods to add ammonia like fish food however this isn’t very predictable as you need to wait for the food to break down and decay before it produces ammonia. You can’t gauge how much your adding and how long it will take to break down meaning that you’re not really creating a consistent level to cope with fish when they are added.

The most accurate method is liquid ammonia like Dr Tims. I love this method because you add so many drops per litre your tank is so it’s such a simple method and easy to do.
I have included an image of what this looks like and in the comments I will include a link to an online calculator which helps you calculate how many drops you need to add in. The calculator is simple you pop in how many litres your tank is and what level you need the ammonia and if there is any current ammonia there and it simply calculates how many drops you need to add. The percentage of ammonia in Dr Tims for the online calculator is 4%. The instructions on the bottle are very simple, for 2ppm you add 1 drop per litre. So for example a 20L tank would have 20 drops added. If it’s 4ppm you add 2 drops per litre. So again for example a 20L tank you would add 40 drops.
Now please bare in mind the drops per litre is a guide, and what I mean by that is although you have a 20L tank you have to consider that so many litres are actually taken up by the decor so the first time adding when you test the next again day you will more than likely have slightly more than what is required so don’t worry.

To make sure your tank is fully cycled and ready for a fish it can take 6 weeks. I know it can take time but we want our beautiful fishes to be happy. Putting a fish in when it’s not ready can cause them stress, some fish may not even make it through the process as it’s effectively poisoning them slowly. Some symptoms they can get are burns from the ammonia which look like red areas that are sore and raw, they can be gulping for air at the surface, their fins can become clamped and they stay listlessly at the bottom, their gills can bleed, they can become lethargic as they will be weak from poor water quality and betta especially can end up with torn fins which can develop into fin rot and or a bacterial infection and the worst outcome could be the fish getting dropsy which is organ failure and there is no cure for this. There is more information on these diseases and conditions under the topics disease
There are so many bad things that can happen that it’s really not worth the risk to have a fish in there suffering this process as it’s 100% not a pleasant experience for them.

You cannot cycle a tank without a good liquid testing kit such as API master test kit which is my preferred one as it’s easier to read or NT Labs multi test kit which I’ve included photos of. The liquid tests are far more accurate than strip tests as these are notoriously unreliable and at times don’t even work and they don’t test for ammonia which is the main factor in cycling a tank. The liquid tests let you know exactly what’s going on as each stage progresses.

There are 3 stages to the cycling process which is ammonia, nitrite and nitrate.
The first stage is ammonia and we will be adding this in liquid form so when we test our water we will expect to see this appear at a certain level. For photo purposes I’ll include just API tests to indicate what I mean, they have a colour indicator chart to show your levels. So generally when we add the ammonia we’d have the ammonia level at either 2ppm for a single betta or 4ppm for one with tank mates.
So when you test your water daily we are looking at the colour of the test, we want it to be at one of the ranges I’ve mentioned and only ever top it up when it drops below that.
For example for the first 3 days the ammonia level could remain at 4ppm and on the 4th day it drops to 3ppm at this stage we need to top it up so that it cycles properly.
What happens when we add the ammonia is we are basically growing bacteria that can eat the ammonia, it does take time for this to happen so be patient.
After a period of time as the bacteria is growing more you will start to see that you are topping up the ammonia more frequently than you did at the start. This is good as it’s establishing itself.
The bacteria doesn’t remove the ammonia it changes it into nitrite which is the next step in the cycling process.
At this stage you will start to see your water tests for nitrite start to increase and this is your indicator that it’s progressing. You just keep testing daily at this point and topping up your ammonia when needed. You will then start to see the nitrite levels dropping. As it’s dropping this shows that another type of bacteria is growing to eat this up, and again this doesn’t remove it, it just converts it into nitrate which is the final stage in the cycling process.

What we are looking for is you adding the ammonia daily and within 24 hours we want to detect no ammonia or nitrite this is when the tank is ready. All you need to do at this stage is a water change to remove some nitrates and you’re ready for a fish. Nitrates are a part of the cycle that can be eaten by plants but we’ll keep it simple and relate a water change to reducing these.
It is safer to allow the tank to reduce both ammonia and nitrite in 24 hours for at least 3 days to make sure that it’s remaining stable.

Ammonia and nitrite need bacteria to establish to cope with these toxins as they are very toxic to fish. Nitrates are the part where it’s us that remove them.
Nitrates are tolerable at levels from 5-10ppm however some tap water supply does have higher nitrates so if your tap is higher it’s unrealistic to keep it within the 5-10ppm range.

Now although the tank is cycled and ready for your fish you can’t stop there, you need to continue to add ammonia until the day before your fish is due to arrive. If you stop feeding the bacteria with ammonia it will simply die.
Bare in mind that it takes 24 hours to process ammonia that’s been added so if you add the ammonia in the evening then want a fish the next morning then bacteria wouldn’t have processed it all by then so only half dose your ammonia.

Water changes aren’t necessary during the cycling process so I’d personally just leave it until the end and do one before the fish arrives, however if you do one this won’t stall the cycle as water holds no beneficial bacteria but what will happen is you’re removing the ammonia you’ve added to cycle the tank, so it’s super important that you check your levels and top back up otherwise you’ve just stopped it properly cycling.
So basically what I mean by this is if you do a water change and your levels are now 0 for ammonia and nitrite this does not mean your tank is cycled it means that you’ve removed the bacteria’s food source. It’s only cycled when you’ve added ammonia daily and the readings are zero for ammonia and nitrite after 24 hours without the aid of a water change.

Now that I’ve explained it in a little detail I’ll recap simply what’s happening.
1. You add ammonia to 2ppm or 4ppm
2. Bacteria grows and eats the ammonia and changes it into nitrite.
3. Another bacteria grows and eats the nitrite and changes it into nitrate
4. 24 hours after adding ammonia you want 0 readings on ammonia and nitrite indicating that the tank is fully cycled
5. Water change to remove nitrates and you’re ready for your fish.

Now just a little extra info.
If you have a tank that’s already set up and established you can borrow some of that media to speed up a new tank.
What to do is move some sponges or ceramic rings whatever you use and pop it into the new filter along with some new sponges or other media.
This can kick start it within a few days to a couple of weeks.
The same rules apply you need to add ammonia to cycle it.

Established filters and tanks with no fish need to have liquid ammonia to keep the cycle going. The bacteria needs the ammonia to feed off so without that it will simply die in less than 24 hours meaning you’re cycling from scratch after this point.