III. Fishless Cycling

Author: Ian Jefferies, AKA Rocker

How to prepare a tank for fish without using livestock

Fishless cycling, as the name suggests, is the method of cycling a tank without using fish. Since we are not using fish, it is the most humane way to cycle a tank. Toxic ammonia and nitrite go unmetabolized during the start of any cycle, causing damage to livestock. The ammonia burns the fish’s gills, eyes, fins, skin, etc, while nitrites decrease oxygen levels in the fish’s blood, causing the fish to suffocate.

But why bother to fishless cycle?
The advantage of this method over the traditional method of using a few ‘starter’ fish to cycle is that the bacterial colonies are established faster and in greater numbers. This allows you not only to introduce your fish earlier to the tank, but also to fully stock it once the cycle is complete. This is advantageous to keepers of malawi’s etc, where large numbers need to be introduced at the same time to be allowed to become accustomed to each other.
As mentioned, this method is a lot quicker than the traditional method. An appropriate comparison of my own experiences shows a fishless cycle taking about 10 days compared to the 30/35 days of the traditional method.

How is this achieved?
The method involves introducing an ammonia source at a high concentration in order to start the nitrifying bacteria in high quantities; much higher quantities than a few starter fish could produce.

The source
Finding a good source of ammonia is the tricky part. There are different types/brands of ammonia solutions on the market, all with varying concentrations. The brand doesn’t matter as long as it contains ammonia solution only, i.e. ammonia and water, nothing else. No scents, perfumes etc. Always check. I found a good source at my local chemist. Then, after reading the ingredients, I phoned the manufacturer and double-checked the ingredients with them. A simple test is to shake the bottle, if it foams then look elsewhere for a better source.

In addition to the ammonia, you will want a good source of bacteria to start the process. The better the source of bacteria and the larger the quantity, the quicker the cycle. Good examples of a bacteria source include:

  • Plants (see separate notes on plants)
  • filter sponge or media
  • squeezing from the filter, or media
  • gravel
  • ornaments and decorations

All these should come from an established, disease-free tank.

There are a couple of other sources that people use, but in my experience, I would not entertain these. These are the commercial products such as, Cycle, Stress Zyme etc., which in my opinion are not only a waste of money but also hinder and delay the cycle. I tried one of these products in a fishless cycle and after the cycle had run for double my usual time, I gave up and reverted back to one of my good sources mentioned.

Note on plants
Although I have had little luck using plants, they can be a good source of the bacteria we need. Provided they are of the potted variety and are planted in ‘rock wool’, they should host a good source of bacteria. It is the ‘rock wool’ that contains the good bacterial colony, as a result of the plants being grown hydroponically in immerse conditions. I feel my unpredictable results were a result of several factors: I didn’t always use potted plants - just cuttings, and I believe the plants used came from an environment separate from livestock, where no ammonia would have been present to feed the bacteria.

The method
To start the cycle you will need the source of ammonia, the source of bacteria and an ammonia, nitrite and nitrate test kit.
Add the source of bacteria to the tank. The water should be at the desired temperature and the filter should be running. Tip - Increase the temperature to the mid to higher end of 80F (26.67C) for quicker results. Be careful not to raise it too much as there may be insufficient oxygen present to develop and support the colonies.
Now add the ammonia in such a quantity to raise ammonia test results to ~5ppm. This is best achieved by simply adding a few drops, and testing. Adding a few more drops, and testing again. Raise the ammonia test results to a reading of ~5ppm.

Now, add the ammonia at the same time every day raising the results to ~5ppm until you find detectable nitrite in the water. So while you are testing your ammonia levels at ~5ppm, also test for nitrite. The nitrite levels will “spike”, as registered by high readings with your test kit. When this happens, cut the amount of ammonia back by halving the reading. Carry on adding this quantity and you should observe the nitrite reading start to decrease. When the nitrite reading is zero, the cycle is complete, but you are not finished yet!

Note:
Be warned that this process is unlikely to go smoothly in low alkalinity/KH water. If the KH is not at or above 3 degrees (or ~50ppm), it should be monitored closely and adjusted. A pH crash is a very real and even likely occurrence, to the detriment of the colonies.

So what has happened?
You have completed the cycle by introducing a source in such a high quantity for large numbers of nitrifying bacteria to convert ammonia to nitrite and then to nitrate. In the process, ammonia is oxidised by one type of bacteria to nitrite. Nitrite is then oxidised by another type of bacteria to the lesser toxic nitrate.
Although nitrate is less toxic than nitrite, the levels produced in a fishless cycle are extremely high. Therefore, the last step is to perform a large water change. I normally do a 70/80% change. Adjust the temperature to the correct temperature for your fish, test your water and if all is well, add any remaining décor and plants and the tank will be ready for your fish.

Since this is a newly created cycle, it is important that you keep a close eye on the water parameters for the first week.

Precautions
Be careful not to ‘overdose’ with the ammonia. Depending on the test kit scale you may well add the ammonia and get a reading of ~5ppm immediately, where as in reality the actual reading may be off the scale. If this happens the ‘overdose’ may well inhibit the growth of the bacterial colonies.

Also, refrain from using any ammonia-removing products in any form i.e., Ammo Lock - use a plain de chlorinator.
It is essential to de chlorinate the water before adding the source of bacteria. Chlorine is lethal to our desired bacteria, so make sure your source - including plants - are kept away from chlorinated water, i.e. untreated tap water.
Be careful of some rocks as well, as they can absorb ammonia. ie. zeolites.

And Finally!
This method has proven to be very successful for me and I have cycled in excess of 40 tanks to date. On average, I look to cycle a tank in around 10 days. The method of introducing ammonia into the aquaria also has the advantage of being able to keep empty tanks ‘ticking over’ with the addition of a few drops of ammonia.

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