Calculating the size of an aquaponics system involves considering a number of factors, including the size and type of fish being raised, the type and number of plants being grown, and the overall goals of the system. Here are some general guidelines for calculating the size of an aquaponics system:
- Determine the size and type of fish being raised: The size and type of fish being raised in an aquaponics system will have a big impact on the size of the system. For example, tilapia and trout are relatively fast-growing and have a high feed conversion rate, so they will require a larger system than slower-growing fish like koi or goldfish.
- Determine the type and number of plants being grown: The type and number of plants being grown in an aquaponics system will also have an impact on the size of the system. For example, leafy greens and herbs are relatively fast-growing and have a high yield, so they will require a larger system than slower-growing plants like tomatoes or peppers.
- Consider the overall goals of the system: The overall goals of the system, such as whether it is being used for commercial production or for personal use, will also affect the size of the system. For example, a system that is being used for commercial production will likely need to be larger than a system that is being used for personal use.
To further calculate the size of an aquaponics system, there are several additional factors to consider:
- Determine the water flow rate: The water flow rate in an aquaponics system is an important factor to consider when sizing the system, as it will affect the amount of water that is needed to properly support the fish and plants. A general rule of thumb is to aim for a flow rate of at least 50 gallons per minute (gpm) for every 100 square feet of grow bed area and or be able to replace the water in the fish tank once or twice pr hour. I.e. if your fishtank is 100gallons, you need 100-200gallon flow to your fishtank every hour. You can measure ammonia levels in your fishtank to see if you have enough flow to your fishtank, it should be very close to or preferably 0 ppm. PS: If you have any ammonia in your fishtank, check your fishtank intake water too, your ammonia source might be an undersized biofilter.
- Determine the fish stocking density: The fish stocking density in an aquaponics system refers to the number of fish that can be raised in the system based on the size of the tank and the amount of feed that is provided. A general rule of thumb is to aim for a stocking density of about one pound of fish per five gallons of water. Remember to calculate using the fish full size weight, you shouldn’t add 100’s of fish fry to a 1000L IBC system and think it’s ok for the long run.
- Determine the size of the grow bed: The size of the grow bed in an aquaponics system should be based on the size of the tank and the number of plants being grown. You can start with a grow bed size that is about one-third the size of the fish tank, but depending on what you grow and type of fish you might need as much as 3x the grow bed compared to fishtank.
- Determine the size of the sump tank: The sump tank in an aquaponics system is used to store excess water from the grow bed, and should be sized based on the size of the grow bed and the water flow rate. A general rule of thumb is to aim for a sump tank size that is about one-quarter the size of the grow bed. It should also be able to store all the water exiting any grow beds and fish tanks if there is a power failure.
- If you follow the general guidelines you should be able to get a system up and running, but the only way to properly size the system is to run the system and take daily water tests, use a log book to write it down so you can follow how the system evolves. Too much nutrients? Add more plants/grow beds. Too little nutrients? Add more fish or reduce amount of plants.
Overall, there are many factors to consider when calculating the size of an aquaponics system, including the size and type of fish being raised, the type and number of plants being grown, the overall goals of the system, the water flow rate, the fish stocking density, the size of the grow bed, and the size of the sump tank. It may be helpful to consult with an expert or refer to online resources for more specific guidance on sizing an aquaponics system.