Aquaponics is an integrated aquaculture (growing fish) and hydroponic (growing soilless plants) system that mutually benefits both environments. Aquaponics uses no chemicals, requires one tenth or 10% of the water needed for field plant production and only a fraction of the water that is used for fish culture (Aquaculture).
The waste from fish tanks is treated with natural bacteria that converts the waste, largely ammonia, first to nitrite and then to nitrate. The fish waste absorbed by plants is pumped to a bio-filter system as a nutrient solution for the growing plants (Grow Bed). The only external input to the system is food for the fish. Both systems complement each other as a single unit, not as separate units.
Starting the Project
First let me explain that you do not have to have a college degree to be successful with aquaponics on the home level. Just like you do not have to understand the chemical process that goes on during combustion in the engine of your car to successfully operate it you do not need to fully understand the complexities of the biochemistry involved in aquaponics.
You do need to know a few things though just as you do to operate your car. If you get the chance to attend an aquaponics course or seminar I highly recommend it. If not there is always the school of hard knocks. Just be sure you start small. That’s what this manual is all about. The first basic of aquaponic is the nitrogen cycle. It is how toxic ammonia fish waste is ultimately converted to not as toxic nitrates.
The Nitrogen Cycle
More than 50% of the waste produced by fish is in the form of ammonia, secreted through the gills and in the urine. The remainder of the waste is excreted as fecal matter, undergoes a process called mineralization which occurs when Heterotrophic bacteria consumes fish waste, decaying plant matter and uneaten food, converting all three to ammonia and other compounds.
In sufficient quantities ammonia is toxic to plant and fish. Nitrifying bacteria, which naturally live in the soil, water and air convert ammonia first to nitrite (Nitrosomonas bacteria) and then to nitrate (Nitrobacter) which the plants consume. Nitrifying bacteria will thrive in the gravel beds and in the water in the system. The plants readily take up the nitrites and nitrates in the water and, in consuming it, help to keep the water clean and safe for the fish.
What the Plants Need
Plants need nutrients in the proper amounts, oxygen, CO2, water and light. They can come from natural or artificial means. Aquaponics takes advantage of a natural process in a controlled environment and fulfills these requirements.
Plant roots need oxygen which brings us to the need for a flood and drain requirement for the growbeds. If plant roots would tolerate continual immersion in water we would not need to drain the grow beds and could simply flow water through continuously. There are several different schemes to accomplish this using timers, float switches or even computer control. The flood valve eliminates the need for such technology.
What the Fish Need
Fish need clean oxygen rich water and reliable feed to thrive. The water also needs to be at the right temperature. Conditions that are tolerable vary from species to species. One would have to get information elsewhere concerning the specific species desired. All you need is an aquatic animal with gills to provide the basic nutrients for the nitrogen cycle to operate and the bacteria to make the conversion for the plants to take up the nutrients. It is a natural process that simply has to have the right conditions to occur.
The bacteria and plants in my system keep the water crystal clear and the water has the sweet smell of healthy creek water. This is one of the basic indicators I use to check the overall health of the system. If it get’s out of balance you will know it. When things die they smell bad. Whether it’s fish or microbes.
The most common cause of problems in a stabilized system is over feeding. The water gets cloudy and the first reaction is to get nervous about the change. I just back off the feed for a day or two. The fish will be fine unless there is a toxin causing the problem. At which point they will probably be lost anyway. The key to all this is to familiarize oneself with the day to day operation and nuances. It will become intuitive after a while. Have fun with this and don’t worry too much.
As far as feed goes it all depends on the fish you are using. I have tilapia in my system. Tilapia are a wonderful choice in tropical climates as they are extremely forgiving as far as water quality is concerned and they are not picky eaters. They are vegetarians and will consume leafy scraps from the garden as well as water hyacinth, water lettuce and duckweed.
They do very well on standard floating fish feed and I have even heard of people feeding them dog food when the fish pellets are not available. Don’t forget about the natural feeds available in your area. There are large amounts of protein flying about in the form of insects and would be attracted by a light suspended over the fish tank at night. Not to mention worms, grubs, maggots, etc.
Download full manual here, more info at www.aquaponics.com/aquaponics/aquaponicsoverview.php
Update: March 15, 2010 – Additional info from Jo Min:
Aquaponics instructional materials (manuals and video) can also be obtained for free from Dr. Melchor Tayamen (Center Chief/BFAR-Munoz, Nueva Ecija), provided you bring your own blank CD/DVD.
source: socalfishfarm.com, aquaponics.com, photo from aquaponicsnation.com