The following water quality parameters are typically of highest importance to
* Dissolved oxygen (DO) is the amount of oxygen (O2) dissolved in water and is measured in units of percent saturation or parts per million (ppm).
* pH is a measure of how acidic or basic the water. pH ranges from 1 - 14. A pH of 7 is neutral, below that is acidic, above that is basic.
* Buffering capacity or alkalinity refers to water's ability to keep the pH stable
and is highly dependent on the amount of minerals dissolved in the water.
* Ammonia is the first product in the nitrogen cycle (Figure 1). In water it exists in two forms and together is known as Total Ammonia Nitrogen (TAN) and measured in units of mg/L or ppm. The two forms of ammonia are unionized ammonia (NH3 or UIA) and ionized ammonia (NH4 + ). You should learn the differences between the two forms of ammonia because it is the unionized
* Nitrite is the second product in the nitrogen cycle. Nitrite is a highly toxic substance that is produced by the oxidation of ammonia by bacteria. It is converted to the nontoxic form nitrate with biological filtration and measured as total nitrite or nitrite-nitrogen, dependent on the water chemistry test kit, in units of mg/Liter or parts per million (ppm).
* Nitrate, the final product in the nitrogen cycle, is usually not measured in an aquaculture setting as it is generally not toxic to freshwater fish and aquaculture test kits often do not carry the reagents to measure it.
The non-mineral nutrients are: hydrogen (H), oxygen (O), & carbon (C) and these nutrients are found in the air and water. In a process called photosynthesis, plants use energy from the sun to change carbon dioxide (CO2) and water (H2O) into starches and sugars. These starches and sugars make up the plant's food.
The macronutrients, required in large quantities, are:
In order to sustain a healthy environment, these substances must be removed from the aqueous environment. Most of the carbon dioxide is eliminated through aeration at the water surface and taken up by plants. The toxic nitrogenous compounds are converted to less toxic compounds via the nitrogen cycle (Figure 1). A group of bacteria known as nitrifiers (e.g.Nitrosomonas and Nitrobacter) transform toxic ammonia into nitrite and then to nitrate via biochemical oxidation. The less toxic nitrate is the final end product after completion of biochemical oxidation that plants take up as fertilizer.
How often you test your water is also important. Start-up systems (at initial stocking of plants and animals) should be tested daily so adjustments can be made as soon as possible (e.g. decrease feeding, increase aeration, water exchange).
After the nutrient cycles are relatively balanced (a minimum of 4 weeks), weekly monitoring may be appropriate. Record (in pencil) all your readings in a data book or waterproof paper. This will aid you when fish stop eating, show signs of distress, or your plants look unhealthy; water chemistries may be out of normal range for optimal fish or plant health. You will know immediately if your daily regiment needs amending.
Recommended water chemistry parameters:
Dissolved Oxygen (DO): 5mg/litre or higher
pH: 6.5 - 7.0 is deemed "ideal" for a well-established system, low 6's -7.5 is fine though. New systems tend to run a bit higher initially... mid 7's to low 8's, but most begin dropping pH shortly after cycling.
TROUBLESHOTING When your test results evidence a current water quality issue;
* Stop feeding
* Check your tank bottom for uneaten food and remove it.
* Increase the flow rate through your system - more water flow means more nitrification and aeration.
* Add salt - at the rate of 1 - 2 parts per thousand. That's 1 - 2kg of salt to each 1,000 litres of water.
* Boost aeration - there are very few water quality issues that will not benefit from more oxygen.
* Change water - if things are not moving quickly in a positive direction. This might be seen in some quarters as wasting water (that depends entirely on what you do with it next) but having your fish die for the want of a water change is just plain dumb. Limit your water change to that needed to address the problem.
The first 6 months of a new aquaponic system can have some challenges, they can take up to 12 months to mature, but once it does all you need to do is feed your fish and pick your vegies.
Kratky, B.A, 2002. A simple hydroponic growing kit for short term growing vegetables. Cooperative Extension Service,
College of Tropical Agriculture and Human Resources. Home Garden, June 2002 HG-42. www.ctsa.org/files/publications/TestingAquaponicWater.pdf
TYPES OF SYSTEMS
There are two main systems: NFT (Nutrient Film Technique) & Medial Filled Growbeds
Media filled growbeds is the simplest system, a growbed is filled with gravel or clay balls. The water from the fish tank is pumped over the growing media in which the plants grow.
Nutrient Film Technique works on a very small amount of nutrient rich water passing through
SEQ Fish Pty Ltd
The Basic Principles of Aquaponics
* Happy Fish * Adequate number of fish * 6 Hours of Sunshine per day * Water Temperature
It is important to have an adequate number of fish in your tank to provide the necessary nutrients to the plants. Do not use any herbicides, pesticides or fertiliser on your plants as this will kill the fish.
You need a position that has around 6 hours of full sunshine each day. If you have a shady area or an area that receives less sunshine than this you will end up with long spindly vegetables with a poor growth rate.
The climate you live in will dictate to a point the kind of fish you stock and during which season. There are many different kinds of fish and crustaceans that like different water temperatures and thrive in aquaponic systems. Thus providing you with many delicious fresh meals.
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