Richard bray

Fish Cycling
Fish cycling is the more natural, traditional method of cycling a new aquaponic system. This process takes up to 6 weeks, and will require daily water tests to check ammonia levels.
The key to fish cycling is to build up your bacteria slowly by only adding a few fish at a time. Start with a few fish, preferably goldfish, and feed them small amounts of food. Goldfish handle ammonia and pH fluctuations better than other aquaponic fish, and they are easy to replace if a few die off.
As the fish produce waste, nitrifying bacteria will be attracted to the system. The bacteria will start transforming ammonia into nitrates,
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which are harmless to fish. However, to avoid high nitrate levels, which can cause an algae bloom, you can put a few plants into your grow beds.
You should begin testing your water before you add any fish. Get a baseline pH, temperature, and ammonia reading, and then add in a few fish. They will begin to produce ammonia as soon as they are in the water, so it's important to have your pumps and filters working to avoid ammonia toxicity.
Many freshwater tests measure total ammonia, which is the total ammonia and nitrate in the system. It’s almost impossible tc distinguish between toxic ammonia and beneficial nitrate on a test, but an increase likely signals a rise in ammonia.
The only way to keep ammonia in check is to monitor pH and temperature. Nitrifying bacteria operate better in a pH range of 6.8-7 and in cooler temperatures. Cover your fish tank and grow beds tc prevent the water from getting too warm, and keep close tabs on temperature fluctuations. As long as the pH remains right below neutral, the bacteria should have the right environment to filter the water.
If your test shows a spike in ammonia, you may have to replace a large amount of water. Ammonia can quickly build up and kill your fish, so if you notice the ammonia levels climbing above 5ppm, prepare 1/3 of the water volume of your system by adjusting the pH and temperature to the proper levels. The pH should be close to 7, and within .3 of the system water, and the temperature should be within 3° of the system water to prevent shocking the fish. Drain off 1/3 of the system water and add the new water. Repeat a water test to make sure this lowered the ammonia below 5ppm.
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Ammonia and nitrate are difficult to distinguish on a water test, but
once your nitrite levels are consistently measuring near 0.5ppm, you have established both types of nitrifying bacteria that are necessary for nitrification. This will take at least a few weeks, but will more likely take a month or two.
Once bacteria have colonized your system, you can gradually introduce more fish and plants. Add half of your fish and plants, and keep testing your water daily. If the nitrite levels remain steady, your system has been successfully cycled, and you can add the rest of the fish and plants, and resume a normal feeding ratio.