Choosing an Aquaponics Pump that matches the needs of your system involves a few things to take into account.
Aquaponics Pump GPH Rating
Most water pumps have a gallon per hour rating that indicates how many gallons of water that pump will move every hour. So you will have to determine how many gallons of water you need to turn over for every hour or two.
For a typical home gardener system a good rule of thumb is that you will need to turn over your system volume at least once every two hours.
This ball park recommendation doesn’t have to be perfect but it’s a good place to start. For example if you have a 100 gallon system then you know you need to be moving all your water at least 50 gallons per hour to get the entire system turned over in two hours.In this case you would need a 50 GPH pump minimum.
Water Pump HH Efficiency Rating
There is more to this calculation then just GPH. How efficient is the pump at different heights since most hobby aquaponics will be moving water upwards. So what is the difference between the top of your grow bed and the top of the water in the tank it’s being pumped from. This is known as head height (HH).
If the difference is 2 feet, then you have to move and elavate 100 gallons of water in two hours. It’s not always a linear relationship between head height and gallons per hour. In addition to the pumps GPH, you will also need to know its efficiency rating.
The details of a pump on the package should tell you what the gallon per hour rating is at different head hieghts in the form of a line graph chart (see below). If it doesn’t, then you will have to contact the manufacturer for the information. The combination of these 2 values ( GPH and Head Height) will determine which GPH rating your pump needs to have.
Best recommendation is to purchase an aquaponics pump that is rated at a height at least one foot higher than your system HH. You are likely to need the head room margin. If the water is flowing to strong you can always insert a valve that slows it down, or even divert the extra water to your tank for additional aeration.
Another possible factor is the distance the water has to flow through the plumbing pipes. This isn’t usually an issue since most hobby aquapnics systems are designed with close proximity between fish tanks and growbeds. However, in larger commercial aquaponic systems there will be more pipe footage the pump must push water through.
As we mentioned before, these are ball park figures and if you’re off by a little bit in the calculations your system will probably run just fine. Each system varies depending on the design, the media, the pluming etc. Just be sure to monitor the system making sure your getting enough oxygenation thoughout.
Submersible aquaponics pumps are limited to 1200 Gallons per hour of pumping power. This is perfectly acceptable for the average aquaponics hobbyist but the larger commercial systems would need more.
Submersible pumps are placed directly in the fish tanks or canal pipes found in grow beds like the NFT design. The water helps to cool down the pump. A fitting on the top, or a hose attached to it pumps the water in the direction needed.
Most pumps will come with a few fittings. There will be two that screw onto the top of the pump. One of these attach to a common sized hose and the other to a smaller hose, both that are capable of pumping water in the direction needed.
Another fitting that is usually provided is called a Venturi. This is a fitting that has a small outlet on the side with a narrow tube attached that sucks in air the the flow of water that is pumped out the top of the fitting into a common sized hose. This will aerate the water so you wouldn’t need to use an additional oxygenation device.
Another consideration is the amount of wattage the pump is using. Aquaponics pumps are running 24/7 so you want to use the least amount of electricity possible for expenses and for the benefit of the environment.
Inline pumps (also known as external pumps) usually generate more power than submersibles and are cooled by the air environment. These are used mostly for larger systems and are rated by horse power instead of GPH.
More Info On These Pumps Here
A sump pump is beneficial for aerating a tank with oxygen and stirring up nutrients. It is also capable of pushing water flow from one tank to another.
Air Pumps are also usefull for stirring up oxygenation in the water. They do this by pumping air at high pressure at low volumes. This benefits plant roots that need the oxygen and fending off aenaerobic decay in grow beds.
Make sure that the packaging indicates whether it’s a submersible or inline pump depending on what you’re using it for.
Be sure that it is designed for pumping water and not some other liquid media.