Since the fish, bacteria, and plants are ALL dependent on water, it is critical that you pay close attention and manage these four water qualities – Purity, Temperature, Aeration, and pH.
For successful aquaponics, it is important to learn how to manage the key elements of a healthy water environment.
The key elements include:
Purity – water that is safe and clean for the fish, bacteria, and plants
- Water that is safe for you to drink is still not ideal for sensitive fish.
- Water should come from a good source such as a well or municipal water.
- Surface water (ponds, lakes, rivers, agriculture ditches, even rainwater) should be avoided since it is likely to have contaminants and harmful bacteria or pathogens that would be difficult to remove to keep your system safe.
- Water should be free of contaminants, disinfectants (such as chlorine and chloramine), heavy metals and pathogens.
- Water will naturally maintain the ambient temperature of where it’s located.
- The type of fish you choose will dictate the optimal water temperature for your system.
- If possible, select fish that will thrive at the water temperature of the system.
- Remember, it is easier to heat water than it is to cool it.
- Attract heat by using a dark colored tank, and retain heat through insulation.
- Use a heater with a control unit that is sized appropriately for the amount of water being heated and the difference in the temperature.
- Dissolved oxygen levels for fish must be above 3 ppm and preferably about 6 ppm.
- It is difficult to have too much-dissolved oxygen in an aquaponics system.
- Warm water holds less dissolved oxygen than colder water
- Dissolved oxygen can be depleted very quickly if the power goes out or the aerator fails. This could cause significant gill damage to the fish if not death.
- Ideal pH is between 6.8 – 7.5 in your aquaponics system. This is a compromise between the optimal ranges of the fish, plants, and bacteria.
- Test pH at least weekly and as frequently as 3 – 4 times per week using an API Freshwater Master Test Kit.
- During cycling, pH will tend to rise.
- After cycling, the system’s pH will likely decline on a regular basis and need to be adjusted up (unless your water is very alkaline).
- Buffer is your water’s natural tendency to return to a particular pH value.
- pH can be adjusted up (more alkaline) or down (more acidic) depending on the hardness of your source water, the system buffer, the nitrification process and the needs of plants.
Source: The Aquaponic Source (Tawnya Sawyer)