Aquaponic systems work by providing plants with nutrients derived from fish waste in a closed-loop circulating system. Fishes, plants, and bacteria work cooperatively to create an ecosystem in which they can all thrive.
The best water pump for aquaponics and hydroponics is chosen based on the flow rate (GPH), head height, power consumption, and pump placement. These factors determine how well the pump performs while circulating water throughout the system.
The water pump plays a critical role in how well an aquaponic system does which is why it is important in choosing the right pump.
There are characteristics of a pump that determine how well it works and by having a basic knowledge of these, you can make an expert decision on the right water pump for your system. So read on! Let’s get the right pump for your aquaponics or hydroponics system.
What’s the Purpose of a Water Pump in an Aquaponics system?
Circulating the water in aquaponics and hydroponics is extremely important. The pumps carry the water to the plants, from the fish or nutrient tanks, where they use the nutrients.
The water then flows back to the tank where the water is again, enriched and the cycle continues.
The function of a pump is like the human heart. The person breaths in oxygen, the lung absorbs it into the bloodstream, the oxygenated blood then goes to the heart where it is pumped to the rest of the body.
It’s the same with aquaponics systems. Although it’s not a sudden death when the pump stops, which we will discuss further later in the article, the system will surely stop functioning if there is no intervention.
Plants in an Aquaponic system depend on getting water enriched with nutrients. The nutrient-enriched water is used by the plants. These nutrients if allowed to build can form a harmful environment for the fishes and this is a vital part of the cycle.
See ourÂ detailed guide on aquaponics and what you need to knowÂ to run a successful system.
After the nutrients are removed from the water. Its flows to a sump which houses the pump. The pump now boosts the pressure of the water and sends it to the fish tank.
The water then flows to the fish tanks where it removes the waste produced by the fish. The rate at which the waste is removed from the tank is determined by the flow of the water from the pump.
The waste is then moved to the mechanical filter where the change in flow rate “knocks out” the heavier matter which settles at the bottom of the filter. The waste can be removed by simply opening a dump valve installed at the bottom of the mechanical filter where the wastes settle.
The water with little waste then flows to the biofilter. The biofilter houses the majority of the bacteria in the system because it creates the right environment for them to live.
See a detailed article on How a Biofilter works here.
In the biofilter, the ammonia from the fish waste is converted firstly to nitrites and then to nitrates in a two-step process called nitrification.
The Nitrates in the water or nutrient-enriched water then flow to the plants, where it is then used for plant growth.
The cycle then repeats itself
How Flow Rate affects the Efficiency of the Pump?
Flow rate is the rate at which the pump pushes out and circulates water throughout the system.
Aquaponics and Hydroponics systems are driven by the flow of water through the system. The flow of this water is measured in gallons per hour or GPH.
These are the units you will see when searching for pumps and also the part of the determining factor in choosing the right pump for your system.
A general rule of thumb is that the pump should be able to recirculate all the water in the system within two hours. Meaning, that if you have a 250 gallons IBC tank, the pump should have a flow rate of at least 125 GPH.
What can Affect Pump Flow Rate?
The flow rate of a pump can be affected by two factors
- Head height – Height at which the pump needs to carry the water
- Restriction in the pump’s discharge piping
Head Height –
The head height is the distance between the surface of the water where the pump is being housed to the highest point at which the water is piped before it reaches its destination.
Rule of thumb – Lesser the Head Height, Greater the flow rate
This is because of gravity. Think about water in a vertical tube resting on a scale. The more water you fill in the tube the higher the water height gets in the tube and the more the water column weighs.
As a result, it becomes harder to push the water out from the tube, the higher the water column gets.
Now, applying this to the pump, it would be harder to pump the water out and therefore less water would reach the outlet of the pipe the higher the water column gets.
Restrictions can cause the pump to become inefficient and not produce the desired flow rate just like head height even if the head height is small.
Restrictions can be in the form of piping size. If the outlet pipe from the pump is small it can restrict water flow just like having a partially closed valve connected to the pipe.
It is recommended to connect the same size of water pipes as the fittings which the pump comes with. This would prevent restrictions and the pump would give the flow rate it was intended to produce.
Other factors such as a blocked suction inlet can also cause restrictions in the flow, which is why the sump or container in which the pump is being housed should be kept clean of debris.
Flow Rate for Different Plant Systems
Different types of systems would require different flow rates to the plants. The recommended flow rate should be applied to the fish tank and the filters to ensure that the waste is not building up and fouling the fish tank.
There is a modified system I have found that works well in keeping the flow rate in the fish tanks while varying the flow to the plants as desired. For me, this system worked pretty well and produced a lot of crops rather than allowing the full flow rate of water to just circulate the entire system.
This system allows you to vary the nutrient water going to the plants depending on what type or size of system you may have and gives greater versatility to your farming needs.
It is difficult to really put a value on the rate at which you supply water to the plants themselves. For example.
In an NFT (Nutrient Film Technique) system the flow rate should be much less than a DWC (Deep Water Culture System) since the rails are slanted slightly so that the water just trickles over the plant roots.
For DWC and grow beds the flow rate can be lesser or equal to the output from the pump and will not affect plant growth.
Flow Rate for Fish Tanks
A faster flow rate would allow for more of the waste produced by the fishes to be removed out from the tank and into the mechanical filter. This results in a clean and clear fish tank and produces happy fish.
On the other hand, a slow flow rate would not be able to remove the waste in the fish tank fast enough. As a result, the tank would become dirty fast. The waste would build up in the fish tank itself resulting in more harmful ammonia being built up in the system causing the death of both fish and plants.
Fast flow rate = Less waste build-up
Slow Flow Rate = More Waste build-up.
For this reason, the flow rate and removal of the heavier matter in the system in the mechanical filter is very important.
Power Consumption of Aquaponic Pumps
Power consumption plays a big role in aquaponics and hydroponics setups. If the system is solar-powered it would even play a bigger part in how you choose the pump for the system.
You would want the power usage to be as low as possible for obvious reasons. The cost of production would drive the feasibility of the entire unit and therefore choosing the right pump for the application is important.
Different brands would feature different power consumption. I have created a table with the top brand of pump from amazon for comparison
|Pump Model||Power Consumption||Flow Rate (GPH)|
|EcoPlus 728310||20 watts||396|
|Simple Deluxe||54 watts||400|
|CWKJ Pump||25 watts||400|
|Ponics Pumps||25 watts||400|
Placing Aquaponic Pumps Inline or Submersible?
Water pumps can be placed in both inline and submersible configurations. Both of these lineups produce the same desired effect for some time.
After some time in service, the in-line configuration can lead to a build-up of sediment on the suction piping.
Additionally, when the pump is on the outside of the sump, the suction has to be connected to the sump with a bulkhead or a uniseal. These connections tend to leak over the course of time.
The suction pipe also has its own limitations as the size can affect the performance of the pump.
On the other hand, placing the pump inside the sump in a submersible configuration has more benefits than placing it inline.
There is no additional piping to cause the problems associated with connecting it from the outside.
Our recommendation is to place the pump submerged inside the sump without the filter padding on the suction. This is because the filter pad tends to get fouled quickly and reduces the efficiency of the pump.
The Best Aquaponics Water Pump
Hydrofarm Active Aqua is the best pump for an aquaponic system because it was tried and tested by us. We bought a 550GPH pump for a 200-gallon fish tank. The pump is running for 3 years without little stopping and maintenance.
The pump features –
- Powerful mag drive construction
- Indoor and outdoor use
- Oil free and environmentally safe
- BPA free safe for aquaponic use
- 6′ power cord
Note: Although the product recommends this pump for a 55-gallon system. From our experience, we found that the flow will be too much for such a small system.
What can cause an Aquaponic Water Pump to Stop?
There are two main reasons which may cause an aquaponic water pump to stop pumping.
- Blockage in the piping
- Power outage
Blockage in the piping can cause the pump to stop pumping especially in an aquaponic system. Pieces of plant roots and leave as are the main culprits.
This can usually be prevented by conducting preventive maintenance. You donâ€™t have to continuously keep watching the pump but a weekly peek into the sump usually works and helps prevent any buildup in the suction piping.
Power Outages –
Power outages obviously would stop the pump. But itâ€™s always a best practice to keep the pump running even if there is a power outage.
Having a backup battery with an automatic switching system can prevent downtime and keep the system running.
What happens if the Aquaponic Water Pump Stops?
Letâ€™s assume you have a CHOP system, the most efficient and widely used system.
If the water pump stops the sump would tend to overflow since itâ€™s the lowest point in the system.
The rest of the system would retain its level relative to the position of the outlet pipes installed on the individual components.
We have written an entire article showing how to maintain levels in an aquaponic system, especially when the water pump stops. See the article here!
Should you Repair a Water Pump or Buy another?
We would recommend repairing the water pump since the only thing that really goes bad is the impeller shaft.
Over the course of time, it either wears out or breaks. Itâ€™s a simple solid ceramic tube inserted inside the impeller which holds it in place.
Having one of these parts on hand can save a lot of time.
Additionally, because they are relatively cheap you can also have another on standby in the event one fails.
Why can Aquaponics Pumps be Submerged in Water without Failure?
Water pumps can be submerged in water because the motor is insulated.
Submersible Induction motors can operate underwater because the electrical circuits are totally insulated from harsh elements such as water.
The heat produced by the motor is dissipated into the water which in turn cools the motor.