Calculating the Best Water Pump Size for Hydroponics and Aquaponics

If you’re interested in hydroponic or aquaponic gardening, you most likely have looked into pump options.

Obviously, a water pump makes things much easier, but you must get the right size.

Pumps that are ill-fitted or unable to provide the proper wattage can have disastrous effects on your system.

Sadly, there are many different factors you need to consider, and there isn’t an easy “one size fits all” pump.

Because there is a lot of confusing information, we want to make it simple for you.

We will help you calculate the hydroponic water pump size by buying the most appropriate water pumps for your hydroponics or aquaponics system.

Before we get straight into pump size, there are some things we need to cover.

What Are Hydroponic system 

Hydroponics is a style of gardening that forgoes the use of soil.

Plants are grown in a way that allows them direct access to oxygen and hydroponic nutrient rich water. 

The roots grow straight into the water to get the hydration they need and can suck up the nutrients to keep them nice and healthy.

It also allows plants to grow around 25% faster and produce 30% more than soil-grown plants.

What is the Difference Between Hydroponics and Aquaponics

While they utilize nutrient-rich water and high oxygen levels without soil, aquaponics is set up in tanks where fish are grown.

The plants and the fish coexist in the tank, and instead of typical nutrient-rich water, it is replaced with fish food and fish excrement that is highly beneficial to the plants.

While this can be a great option, the water must be changed very frequently, and you need to make sure the fish thrive in the environment;.

Otherwise, the dead fish can wreak havoc on the ecosystem.

Why Do You Need water Pumps for your system? 

Because hydroponic systems remove the soil aspect of gardening, water pumps are needed to make up for what the soil helps provide.

This includes airflow and the creation of a movement to avoid stagnant water.

Sadly there is not a “one size fits all” pump, and you have to consider several factors to find the pump you need.

Hydroponic and aquaponic systems require different types of pumps, and the size of your system will require larger or smaller pumps.

Types of hydroponics water pumps for commercial or hobbyist growers? 

There are a few different types of pumps that do different things.

To keep your hydroponic system working smoothly, it may require other pumps for different things.

Peristaltic pumps

This is a small auto-dosing pump that typically comes with purchasing the main pump.

Air pumps

Aerating the water by pumping low volumes of air at high pressure is done with air pumps.

This is important to get oxygen to the roots so decomposition doesn’t occur.

Sump pumps

A sump pump is needed to move the water from one sump tank to another.

Sump pumps are also used to create turbulence, greater oxygenation, and mix the water’s nutrients.

Sump pumps are typically submersible.

How To Determine The Right water Pump Size For aquaponics or hydroponics system

It is essential to know how much water you need in your system and how quickly you can cycle that water through your system.

It is typically recommended that you do a complete cycle every two hours, but you can play around with it and determine if you want more or less.

Once you know how quickly you want this cycling to occur, you can easily determine the desired pump GPH

To do so, divide the total gallons of the system by the total amount of time you want per cycle.

Then you can look at the chart provided on the pump to figure out how efficient the pump will be based on the head height of your system.

If the effective GPH of the pump at the head height you need is below the desired level, you should go up in size.

For example, if you have a 200-gallon system and want a complete cycle every two hours, divide 200 by 2 to equal 100 GPH.

You then need to measure the head height of your system.

Now you need to find a 100 GPH pump and look at the chart on the back to check the efficiency at your desired head height.

If the efficiency is not what you’re looking for, you’ll need to go up a pump size until you find the efficiency you need.

It is important to remember that even when following this system, there will still be a loss of efficiency of about 15 to 30% just from going through your system.

So when in doubt, it is better to go with a more robust pump than what you think you need to be on the safe side.

Sizing a Water pump for hydroponics or aquaponics 

When you look for pump things, they tend to end up far more complicated than they need to be.

We want to make it as easy and hassle-free as possible because it isn’t that hard.

Following simple formulas and getting the required information can make finding suitable water pumps for your system quick and painless.

How Much Water Can Be Pumped (GPH) 

The amount of water being pumped is measured in gallons per hour (GPH).

Luckily many pumps have adapters to increase or lessen the amount of water being pumped so you can adjust as you need.

Larger adapters increase the maximum GPH, while smaller adapters decrease the maximum GPH.

This is incredibly helpful because it means you get three different hydroponic water pumps out of the adapters and can save quite a lot of money in the long run.

It also allows for some wiggle room when buying a hydroponic water pump.

So, if you need something between two pumps, you only need to buy one and use the adapter.

To calculate the GPH, you require you to need the flow rate multiplied by the units with that flow rate.

If you want to convert gallons per hour into gallons per minute (GPM), you simply divide the GPH by 60.

GPH vs. HP

Some pumps measure in horsepower (HP) rather than GPH, so it is important to recognize the difference and compare the two.

GPH quantifies the amount of water the pump can move while the HP covers the motor’s power.

Typically the HP is found in inline model pumps because they cannot be submerged.

Here is a site that can help you with conversions to make it simple.

Measure System Head Height

When water needs to be pumped up vertically, you need to consider the head height.

Backwater pressure is required to force the weight of the water up, and when there is no longer a pressure to push the water up.

At this point, it has reached the maximum head height.

It is essential to remember that getting over even a slight vertical incline requires knowing the head height of the pump.

Usually, a chart on the package can help indicate the maximum head height the pump can provide.

When in doubt, go with the pump with the highest head height because it typically also has the highest PSI pressure.

To measure the system head height, you need to find the distance between the highest point your water must get to and the water line in the pump.

The difference between the two is your head height.​

Combine GPH and Head Height

It is important to remember that the higher the pump must push the water up, the lower the GPH.

So even if your pump is only going a couple of feet tall, it’ll affect the GPH, and you’ll not get the full power of the pump.

Anything over a foot high will always decrease the power the pump can provide.

All pumps come with a chart that outlines the combination of GPH and head height to make it easier to find what you need.

Things to consider when choosing The Best Water Pumps For Hydroponics and Aquaponics 

There are other things to consider besides the size of the hydroponic pump.

Do you want the pump in the tank or outside? Do you need a timer?

What about wattages and air pumps? We can help you sort that out as well.

Inline Vs. Submersible Pumps 

These are the two main types of water pumps.

  • Submersible pumps
  • Inline pumps

Submersible pumps are placed directly into the water while inline pumps sit outside of the tank.

Submersible pumps are cooled by the water (further cooled by a hydroponic water chiller), and the air cools the inline pumps.

The most significant deciding factor when choosing an inline or submersible pump is the amount of power you need.

Hydroponic submersible pumps are more equipped for smaller DIY hydroponic systems, while inline has the capability for larger-scale gardens.

Pump Timers

Timers are particularly useful for hydroponics because it allows your system to function as you want without you constantly having to be there.

Especially with mists, drips, and flooding methods where inaccurate timing can dehydrate and kill your plants.

Timers are also great energy savers and can help keep your power bill down each month.

To keep everything running smoothly, you need to make sure your timer is set correctly.

You should check at least once a week to make sure it is working correctly.

You should also research and find a timer that can handle your needs, rather than buying the cheapest one.

How Many Watts Do You Need 

The water pumps will specify how many watts it needs to run on the package or specifications.

It is essential to use the smallest wattage amount possible because higher wattages mean higher electricity bills.

Especially when you’re running your hydroponic system 24/7, smaller wattages can save you a lot of money every month.

Oversized vs Undersized or Exact Sized 

The rule of thumb is that it is better to be oversized than undersized because you may want to upgrade your system in the future and require more power.

Higher capacity still allows you to adjust, but it guarantees you will have enough power rather than not enough. 

It is also helpful to have two pumps working in tandem than one to ensure the system will still have power if one fails.

You will lose plants if the pump fails, especially with hydroponic systems where the roots are exposed.

Why Do Some Hydroponic Systems Need Air Pumps?

The rule of thumb is that a system with fully submerged roots needs an air pump. Without this, the plants will die from drowning.

When considering buying the best hydroponic air pump, it is essential to remember that you need at least one watt for every gallon of water.

The more oxygen your plants have access to, the better because it allows for better growth.

There is no need to spend hundreds or thousands of dollars to get the biggest pump, but a bigger pump won’t do any harm.

Differences in Systems

Drip Irrigation SystemPin

There are several types of hydroponics systems, and it is essential to know what they all mean to understand what they do and what you need.

Wick Hydroponic Systems

This is the simplest and cheapest form of hydroponic system, so it is ideal for beginners.

It is a passive-style system without moving parts and draws in nutrients via a wick.

The wick connects the plants to a reservoir and draws up the hydroponic nutrients the plants need.

This system is ideal for smaller plants, but the wick method doesn’t move fast enough for larger plants.

Because it is designed for basic systems and smaller plants, you only need a simple pump to handle this.

Ebb and Flow Hydroponic Systems

This is also referred to as the “flood and drain” method and utilizes a timer.

The pump regularly floods the grow tray with a nutrient-rich solution from a reservoir and then drains it back out to the reservoir pool.

This should occur at a set time several times throughout the day. 

To calculate the hydroponic pump size, you must first know the water volume you need to move and then the head height.

If you have multiple growing chambers, you simply multiply the number of chambers by the water volume.

Nutrient Film Technique (NFT)

NFT does not require a timer; instead, the pump displays a constant flow of nutrients. This system forgoes the growing medium and instead suspends the plants on a plastic tray with the roots dangling down.

The roots hang right into the nutrient solution, so this method requires regular maintenance to keep everything running smoothly, or the plants can dry out and die.

Because this system relies more on the constant flow of water rather than an ample supply, you can get away with less water and a strong pump.

They also typically have downward tubes to deliver water instead of having to force the water upwards.

The biggest thing is to keep things flowing on schedule, and as long as that happens, you do not need an overpowered pump.

drip irrigation pump selection

By using a timer, a drip irrigation system allows drops of nutrients to be absorbed and delivered to each plant’s base. The drops are continuous and can either feature a recovery or non-recovery reservoir.

Recovery means that the nutrients are returned to the main base to save them and reuse them later, which is cost-effective.

The non-recovery method lets the used nutrients run off and drains away, which is not cost-effective but helps maintain the proper pH levels.

The result is that the nutrient solution levels stay constant without error.

Sadly figuring out a hydro water pump for a drip method can be more difficult because there is no simple formula to follow.

It all comes down to various factors, including plant size, the number of drippers you use, your timers, a system set up, and humidity levels.

The simple version focuses on water pressure and considers the more dippers and plants you have, the greater the pressure.

Aeroponic Hydroponic System

Aeroponics is one of the newer hydroponic systems and is more high-tech than the others.

Similar to NFT, plants do not have a growing medium.

The crop or plants are suspended with the roots in the air, and the nutrients are supplied to them via a mist.

Timers are used to pump the mist every few minutes and must be maintained.

If the pump or timer malfunctions, it can cause the roots to dry out and the plant to die.

There are two types of aeroponic systems, high pressure, and low pressure.

High pressure requires between 60 and 90 psi and typically relies less on a water pump in favor of a pressurized tank.

The lower-pressure method is more common and uses a submersible pump.

Sadly submersible pumps don’t give you a psi measurement, so a rule of thumb is to go with a hydro water pump with a higher head height to make sure you get enough pressure.


Anyone can get into hydroponics, regardless of their technical abilities or mechanical know-how.

Don’t let the wordy and confusing instructions scare you away from trying out hydroponics.

Thank you for letting us help you navigate the hectic so you can enjoy hydroponics as you should.

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