Water Pumps for Hydroponics or Aquaponics: How to Choose the Right Size for Your System?

If you're interested in hydroponic or aquaponic gardening, you most likely have looked into pump options. Obviously, a pump makes things much easier, but it is crucial that you get the right size. Pumps that are ill-fitted or not able to provide the proper wattage can have disastrous effects on your system.

Sadly there are a lot of 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 out there, we want to make it simple for you and help you spend less time trying to find out How to Calculate Your Hydroponic water Pump Sizing and things to consider before buying the best Water Pump For Aquaponic or Hydroponic system, and more time enjoying your plants.

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 then direct access to oxygen and nutrient-rich water. 

The roots grow straight into the water so they 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 the soil grown plants.

What is the Difference Between Hydroponic and Aquaponic: 

While they both 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 the 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 A Pump? 

Because hydroponic systems remove the soil aspect of gardening, pumps are needed to make up for what the soil helps provide. This includes air flow and a 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.

What Kind of Pump Do You Need? 

There are a few different types of pumps that do various different things. In order to keep your hydroponic system working smoothly, it may require different pumps for different things.

Peristaltic pumps: This is a small auto-dosing pump that typically comes with the purchase of 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 the oxygen to the roots, so decomposition doesn’t occur.

Sump pumps: In order to move the water from one sump tank to another, a sump pump it needed. Sump pumps are also used to create turbulence, greater oxygenation and mixing the nutrients in the water. Sump pumps are typically submersible.

How To Determine The Right water Pump Size For Your System

It is important to know how much water you need in your system and how quickly you need to cycle that water through your system. It is typically recommended that you do a full 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 you want a full 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 then 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 stronger pump than what you think you need, just to be on the safe side.

Sizing a pump for hydroponics or aquaponics 

When you look for pumps things 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 really isn’t that hard. Following simple formulas and getting the right information required can make finding the right pump 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 so you can increase or lessen the amount being pumped so you can adjust as you need.

Larger adapters increase the maximum GPH, while the smaller adapters decrease the maximum GPH. This is incredibly helpful because it means you get three different 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 pump so if you need something in between two pumps you only need to buy the 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 how to compare the two. GPH quantifies the amount of water the pump can move while the HP covers the power of the motor.

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, it has reached the maximum head height.

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

There is usually a chart on the package that 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 ends up being.

So even if your pump is only going a couple 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 heads height to make it easier for you to find what you need.

Things to consider when choosing a pump 

There are other things to consider besides the size of the 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 pumps for hydroponics. Submersible pumps are placed directly into the water while inline pumps sit outside of the tank.

This is because submersible pumps are cooled by the water, and the inline pumps are cooled by the air.

The most significant deciding factor when choosing which option is the amount of power you need.

Submersible pumps are more equip for smaller, hobby gardens, while inline has the capability for larger scale gardens.

Pump Timers

Timers are fantastically useful when it comes to hydroponics because it allows your system to function as you want without you always 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, and you should check at least once a week to make sure it is working properly.

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

How Many Watts Do You Need 

The water pump will specify how many watts it needs to run on the package or in the specifications. It is important 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 so you can ensure the system will still have power if one fails. Especially with systems where the roots are exposed if the pump fails you will lose your plants.

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.

To find the best hydroponic air pump for your needs, it is important to remember that you need at least one watt for every one 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

There are several types of systems available for hydroponics, and it is important to know what they all mean in order to understand what they do and what you need.

Wick Hydroponic Systems

This is the simplest and cheapest form of hydroponic systems, 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 nutrients as 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. This occurs at a set time several times throughout the day. 

To calculate the pump, you will need 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, but 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 a large supply of it, 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 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 Hydroponic System

Utilizing a timer, this system allows drips of nutrients to be delivered to each plant’s base. The drips are continuous and can either feature a recovery or non-recovery reservoir.

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

Drip Irrigation System

Drip Irrigation System

The non-recovery method lets the used nutrients run off and drain away, which is not as cost-effective but helps maintain the proper pH levels. This means that the nutrient solution levels stay constant without error.

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

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

The simple version is to focus on water pressure and consider the more dippers and plants you have, the greater the pressure.

Aeroponic Hydroponic System

This is one of the newer hydroponic systems and more high tech than the others. Similar to NFT, the plants do not have a growing medium. They 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 rely 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 pump with a higher head height to make sure you get enough pressure.

Takeaway 

Anyone can get into hydroponics, regardless of your technical abilities or mechanical know-how. Don’t let the wordy and confusing instructions scare you away from trying out hydroponics, and let us help you navigate the hectic so you can enjoy hydroponics as you should.

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Lindsey Hyland grew up in Arizona where she attended University of Arizona’s Controlled Environment Agriculture. She has supplemented her formal education by working on various organic farms, including spending a semester abroad in India.

Growing and/or raising just about anything gets her excited. She is especially passionate about environmental justice and low-tech, sustainable ways to better run small-scale farms and homesteads. Lindsey started Urban Organic Yield to discuss gardening tips and tactics.

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