The beginning aquaponic gardener is often times very excited to get started with their system and ready to get those fish producing high quality fertilizer for their plants. Many beginners are so excited they end up ruining their system. It is important to take things slow to make sure you have it all done properly before you begin.
In an aquaponics system, the fish eat whatever feed is made available to them and they then excrete the waste in the forms of urine and fecal matter. The fish poop is pumped into the grow bed where it can be converted by bacteria. The nitrifying bacteria neutralize the waste and convert it to substances that are harmless to fish and beneficial to plants. This cycle is called nitrification.
In order for the nitrification process to take place, there needs to be enough bacteria to handle the amount of fish waste that will be running through the system. Usually the simple conversion for volume of water to volume of grow space can be as low as 1 to 1 or as high as 1 to 3. Essentially, the more surface area the bacteria have to live on, the more capacity for waste management you will have. Many systems are media based systems which really just provides more surface area for these little critter to cling to. In my opinion a media based system is easiest system to work with. By providing gravel, hydroton, or other inexpensive aquaponic growing media.
So, the question remains. How do I get my system to have enough bacteria? This is simple. Bacteria are readily available in the air around us. Do not ever buy bacteria. These bacteria will congregate wherever there is food for them. The simplest form of food is any form of liquid waste. In fact, ammonia is commonly used because it is a form bound up nitrogen. Some people actually use urine as their source of ammonia, but this can contaminate the system.
Before you add your fish, simply add a cap full of ammonia per 50 gallons of water to your system. In a few weeks you can test your water (with an aquarium test kit) and see how much ammonia is there, how much nitrites and how many nitrates there are. Once you have plenty of nitrates and not much ammonia, you’re good to go. It’s now safe for fish. Add the fish and let your aquaponics system take shape!