So you have decided to get started in the world of Aquaponics. It's best to start with an aquarium that has been running for at least several months, but if you don't have that, here's what you need to do to get started.
This is not THE way to start a aquarium, it is just a way that has worked quite well for me. It takes a little longer, and you don't get that immediate satisfaction, but this method will start an aquarium reliably.
While all you need to start an aquarium for aquaponics is a container for water, a pump, lights, and a growbed, you may find it easier to buy an aquarium kit. An aquarium kit will come with all the bits and pieces needed to set up a running, healthy aquarium.
First thing first. When you bring home your new aquarium, do not bring fish home at the same time. Wait at least a week before you add any fish to the aquarium. Set the aquarium up and let it run for the first week. This does a couple of things.
At this point, you want to start testing PH and ammonia. If any corrections need to be made, now is the time to do it, before there are fish in the system.
After the first week, if the testing results are good, you can add fish. Only add 1-2 fish. The fish you should add should be small and hardy. If you have an idea of what you want for fish in your tank, ask the fish store what's the hardiest of that list, and get 1-2 of those. The reason to add only a couple of fish is that we need to 'cycle' the aquarium, meaning to grow the biological filter that processes the fish waste into plant fertilizer. These bacteria grow slow, and if we add too many fish, we quickly pollute the aquarium faster then the new bacteria can clean it. Feel free to use a product that contains the bacteria and use it to it's directions. These bacteria need to take residence in your filter medium and growbed and such, which again, takes time.
You can add plants to the system at this point. Start with seeds if your chosen system will allow for this. By starting with seeds, you have a few days to a few weeks before the seeds sprout and start consuming the nutrients in the water. This is good, because there aren't enough fish to support a lot of plant material yet.
Monitor the ammonia daily. You should see the ammonia levels start to climb after the first few days. If it gets in the danger zone, quit feeding your fish for a couple of days, and do a partial water change. Repeat the water changes daily if needed until the ammonia levels come back down. You can feed your fish every day that the ammonia isn't dangerous or every 3 days if it stays high. Once the ammonia levels have climbed and come back down to 0 or after 2 weeks - which ever is LONGER, you can add more fish. Either enough bacteria have been grown to handle the current fish load, or the number of fish are low enough that the bacteria could keep up.
An indication that the ammonia levels are high are the fish 'gulping' and bright red gills. If you see this behavior, test for ammonia and do a partial water change immediately. Another sign of trouble is the fish gulping for water right at the top of the tank. This may be a sign that you need to aerate your tank more.
When you add more fish, double the total number of fish in the system. So you should get 1-2 more at this time. Then monitor the ammonia levels. You should see the same rise and fall of the levels. This time, it may not go up quite as high or for as long and come down quicker. This is good. It's probably going to take at least a couple of weeks to get the ammonia levels down to 0, sometimes as long as a month.
For the 3rd round of adding fish, if you have been fighting the ammonia levels, only add a couple more fish. If you are keeping the ammonia levels down, and the aquarium is adjusting well, double the number of fish in the tank.
Keep this process up, adding more fish as to double to total number of fish every month or so until you have reached the number of fish you have determined your system will hold.
While your adding the fish, the bacterial biofilter is growing, your plants are starting to grow. You are growing a balanced ecosystem in your aquaponics system.
It may sound odd, but an aquaponics system doesn't really 'mature' for a couple of years. Many people are reporting that some plants just don't like to grow well in a new system, but grow great a few years later.