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Keeping a Constant Water Level in an Aquaponic System

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Aquaponic systems work by supplying nutrient-rich water derived from the processed waste from the fish. Maintaining a constant level within the various components is important in an aquaponic system since the functions they perform can be affected by a change in level.

Constant levels in aquaponics and hydroponics systems are maintained by properly designing the system such that the outlet piping of the individual components is placed at the specific height or level of water you wish to maintain.

Maintaining a constant water height is critical in aquaponics and hydroponics and there are a few tricks when it comes to piping that makes these components work efficiently. We are going to explain how to do just this further in this article.

My Aquaponic setup

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The Aquaponic Equipment Essentials that I use in my system.

Where should you Keep a Constant Water level?

This design is a fail-safe method to maintain a constant water level in the event that there is a great loss of water in the system caused by a broken water pipe. The outlet piping allows the water to leave the various components while holding a constant level.

Water is the medium that allows all the functions in an aquaponic system to take place.

An aquaponic system is made out up of several components where water levels should be held at a constant height
These components are:-

Fish tank
Mechanical filter
Planting system

Fish tank

The fish tank houses the fishes or other aquatic animals required for the system. Here the fishes carry out their basic day-to-day activities which in turn provide nutrients for the plants.

You don?t want for any reason, to lose the level in the fish tank since it would result in the death of the fish.

Here is a simple piping arrangement that would ensure all the waste is removed efficiently from the fish tank while maintaining a constant level.

The ?L? shape arrangement with an open-top removes all the waste, while the open-top prevents the water from being sucked out like a siphon if the preceding components develop a leak.

Mechanical Filter

There are also different types of mechanical filters that can be used.
Here too the water level should also be kept constant.

The outlet piping is positioned such that it holds the level at the point where it is connected to the vessel.

At this point, there is also minimal water turbulence so that only clean water with only the lighter material flows towards the biofilter.


One of the main functions is the nitrification process

Nitrification is a process by which bacteria convert ammonia derived from the fish?s waste into nitrites and then to nitrates.

Nitrates are the main nutrient plants use for growth.

These bacteria which are mainly housed in the biofilter thrive in water and depend heavily on the correct water conditions to continue to carry out their jobs.

This is why it is important in holding a constant water level in the biofilter.

Using a similar arrangement as the fish tank, the outlet piping is connected and made to extend down to the bottom of the biofilter.

This is important since the water coming in should have some resistance time within the filter for the bacteria to convert the ammonia to nitrates.

By having the outlet pipe extend down to the bottom and the inlet pipe at the top, the time it takes for the water entering to pass through and leave the biofilter is greatly expanded.

The vent at the top of the outlet piping also prevents the water from being sucked out in the event of a leak further in the system.

See our article on how a biofilter works.

Planting system

Plant systems such as DWC (deep water culture) or modified DWC pipes also require the water to be held at a constant height so that plants can get maximum absorption of nutrients and oxygen.

Plants in modified pipe DWC systems are held in place by net cups fitted into holes cut into the surface of the pipes at regular intervals based on the crop requirements.

The roots from these plants are allowed to dangle above the water surface. This makes it possible for nutrient-root shoots to grow into the water for nutrient absorption while oxygen-absorbing roots grow above the water.

It?s kind of like a Dutch bucket system.

If the water level is allowed to rise too high the roots may not get sufficient oxygen causing impaired growth.

On the other hand, if the water level is allowed to fall too low, the plants will not have many nutrients to absorb and would eventually die.

Here is a simple arrangement where the pipes are placed at the desired height in the pipes so that the water level would remain constant.

The Sump

The sump houses the pump. The pump is the heart of the system and circulates the water throughout the system. If for some reason the water level goes too low in the pump will stop working since there will not be any water to pump.

The overall effect is that water circulation will stop.

With all the above-mentioned components and piping design in place, whenever water circulation stops the system components will just hold the level at which the outlet piping is installed.

This is a fail-safe method to prevent catastrophe in the event of loss of water circulation.

Now back to the sump. The sump should be placed at the lowest point in the system since the pump does the work of lifting the water to the fish which is then fed by gravity to the rest of the system.

Maintaining the level in the sump is as simple as installing a float switch which allows water in from an external source whenever the water level drops.

This small amount of ?makeup? water can be pipe water. Pipe water however can cause an issue if too much is used because it may contain chlorine which can be harmful to the system.

In this case, it should cause much of a disruption as only a small amount of water is allowed into the system at a time, just for topping up purposes.

Aquaponics and hydroponics systems are subjected to water loss from evaporation and water can be made up automatically by simply installing afloat.

Systems where You don?t Need to Maintain a Water Level

NFT Systems
Grow Bed Systems

NFT systems

This type of system works by allowing water to just trickle over the roots of the plants within a slanted pipe rail and does require an actual level to be held within the rails.

Plants with large root systems like cucumbers can cause blockage in the outlet piping causing water to back up.

If the level is held up in an NFT system, only the plants closer to the end will get affected since the water will end up flowing out of the cups at that point.

This, however, can lead to the loss of a lot of water and vital nutrients in the system.

So keeping the outlet piping clean and root-free at all times will be beneficial to the entire system.

Check our article on the best plant to grow in an NFT system.

Grow-bed system

Grow beds are usually outfitted with bell siphons which allow the water level to build intermittently to provide nutrients for the roots after which it is sucked out and drained allowing the roots to get the oxygen they need.

What to do in the event of a large water loss?

When a large amount of water is lost in an aquaponic system, a large number of nutrients will also be lost.

Surprisingly plants can survive will little nutrients at this time but there will be a need for some intervention.

My recommendation is to keep a reservoir of settled water or rainwater on standby whenever this may occur.

Now, this is not just emergency planning but it can also be used whenever you are replacing the fish after cleaning out the system.

Pipe water can also be used but sometimes there may be small amounts of chlorine in the water which can cause harm to both fish and plants. So be careful when using large amounts of piping water in the system.


Maintaining a level in an aquaponics or hydroponics system is important and can have multiple benefits when it comes to the fishes and plant health.

Simple piping arrangements can lead to a clean fish tank, properly working biofilter and a fail-safe method in the event of a line failure in the system.

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