Sump Tank in Aquaponics: Do You Need One?

You often hear people talking about sump tanks in aquaponics systems, but as an aquaponics beginner, you wonder what exactly is the purpose of a sump tank, and do you really need one for your own aquaponics system? Sounds confusing, right? But don’t worry. This article will share what an aquaponics sump tank is, how it works, and how to choose the right sump tank size for your aquaponics system if you need one. 

What is an Aquaponics Sump Tank?

A sump tank is an additional tank added by aquaponics growers with at least a 1:2 fish tank to grow bed ratio. The fish tank is not proportionate to the grow bed, so providing water to multiple grow beds could result in low water levels in the fish tank, which could be detrimental to the fish. A sump tank collects all the water drained in the grow beds, where it is pumped back to the fish tank. This ensures that the water height in the fish tank is maintained regardless of how empty or full the grow beds are. A sump tank also helps improve aeration in the system as this process helps increase the dissolved oxygen level for the fish.


Aquaponics System Design

Are Sump Tanks Needed in Aquaponics?

Many aquaponics growers often find themselves wanting to increase plant production by adding more grow beds. This is great because it means they are successful with their first system; however, by expanding or adding more grow beds, more water will be used, which will lead to lower water levels in the fish tanks. Low water levels in the fish tank will have a negative impact on fish health and wellbeing. So using a sump tank is one of the solutions many aquaponics growers applied to increase plant production without adding a new fish tank

Although helpful, a sump tank is not an essential component in an aquaponics system. Many aquaponics designs (usually small aquaponics designs) do not use sump tanks, but they are still thriving. However, if you want a larger system with multiple grow beds, then a sump tank can be beneficial because it helps maintain the correct water levels in the fish tank. By using a sump tank, you are also creating a healthy aquatic environment for the fish. 

Aquaponics Sump Tank Size

One common question about sump tanks is, how big should the sump tank be? Well, since the sump tank is a water collection tank, it should be located at the lowest point in the system so that the water will always flow downhill to the sump tank. The sump tank should also hold or handle the grow bed’s total volume of water. The simple calculation of the volume of water in the grow bed is approximately ⅓ of the volume of the grow bed media you use in your system. 

Aquaponics Sump Tanks Designs

The two most popular sump tank designs are CHOP/CHIFT PIST and the CHOP 2 aquaponics system designs. To help you decide what sump tank will work best for you, we will briefly explain it below.


The CHIP PIST/CHOP stands for Constant Height One Pump/Constant Height in Fish Tank-Pump in the Sump Tank.A CHOP to CHIFT PIST system consists of a grow bed, fish tank, and a sump tank. The water pump in the sump tank pushes the water to the fish tank continuously, and the water is fed to the grow bed by gravity. The water is then drained back into the sump tank through the bell siphon. This system design effectively eliminates fish stress because the water levels in the fish tank will not fluctuate, and great if your system uses multiple grow beds. This design is much simpler compared to the CHOP2 design and is advisable for beginners in aquaponics.

CHOP/CHIF PIST Aquaponics System Design
  • CHOP 2

With CHOP 2 aquaponics system design, the pump in the sump tank sends water into the fish tank and grow bed simultaneously by using a dual loop system. One advantage of using the CHOP2 system is that it will be easier to add more grow beds in the future, as long as the tank can hold the total volume and you are using a reliable pump.

CHOP 2 Aquaponics System Design


As mentioned above, a sump tank is not a requirement for an aquaponics system. But it could help your system become more successful by taking care of water level fluctuations in the fish tanks if you have multiple grow beds. A sump tank also helps provide a healthy environment for the fish by enabling aeration and avoiding fish stress and diseases. So if you want to add more grow beds to your system, a sump tank could definitely help. Thank you for reading our article, and feel free to leave your comment below. 

2 Responses



August 26, 2021

The explanation on the purpose of sump tank is great, simple and easy to understand. In the diagrams provided is it corect to say the grow beds act as the biofilter? I intend to DIY commercial aquaponics. Is it corect to put a separate biofilter in brtween the fish tank and the sump tank. Your advice is very much appreciated, thank you.



July 27, 2021

Thanks for the advise and tips above which will be priceless when I set up a commercial Aquaponics operation.
Any advise relating to commercial operation will be much appreciated.
Thank you

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