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Aquaponics is more than just raising plants and fish together in an artificial ecosystem. Much of its success comes from the balance between all living organisms involved. To ensure this balance, one of the most important factors to consider is the pH level. Getting the right pH can be tricky since plants and fish can have different requirements. However, there is always that ideal range in which organisms can thrive. So what is the best pH for aquaponics? How can you verify that your pH range is correct?
The best pH for aquaponics is between 6.8 and 7.2. This range is considered a happy medium for plants and fish since they each have specific pH requirements. And to arrive at the right pH level, you need to have a reliable pH meter. Five of the best ph meters for aquaponics are:
- Bluelab PenpH
- MW 100 pH Meter
- Apera Instruments pocket pH meter
- Hanna Instruments pH meter
- Billiony Digital pH meter
In this article, we’ll cover the basics of pH, how to test pH in aquaponics, the different pH meters recommended by most experts, and the criteria to consider when choosing the best one for your needs.
Understanding pH in Aquaponics
For many beginners, getting started in aquaponics gardening can appear to be a somewhat complicated process on the surface. This is primarily due to the frequency of maintenance required to ensure the ecosystem is environmentally balanced, which often comes in the form of checking various data readings on devices. Checking pH is high on the list of priorities of most aquaponics practitioners because it is usually a clear indicator of the system’s overall health.
To understand the pH scale, it is first necessary to know the science behind the concepts of alkalinity and acidity.
What is alkalinity?
Alkalinity is the water’s capacity to resist neutralizing acid. Water with high alkalinity means it usually has high concentrations of calcium carbonate, which will then reduce the water’s acidity, and make it more alkaline, basic, or has a pH of more than 7. The higher the number, the more alkaline the water is.
What is acidity?
Acidity, on the other hand, is the water’s capacity to neutralize alkali, making your water acidic with a pH level below 7. Acidic water is characterized by more H+ ions in the water. To make it easier to remember, the lower the number, the more acidic the water is.
Factors That Influence Ph In Aquaponics
Surprisingly, there are many different factors, both internal to the system and external, that affect the overall pH of an aquaponics ecosystem. It’s important to note that movement along pH scale will happen inevitably from time to time, and it doesn’t necessarily mean that your plants or fish will suffer immediately as a result. However, prolonged exposure to poor pH conditions can lead to problems if not remediated.
Here is a list of factors that are commonly known to affect pH levels in aquaponics:
- Water hardness – tap water likely contains minerals and salts that can increase water pH
- Choice of growing media – limestone and marble have been known to increase pH because of their calcium carbonate levels
- Materials used to create your system – concrete tanks, particularly residual concrete dust, can elevate pH level
- Water quality – too much leftover fish feed can increase pH
- Age of your system – note that a new system is expected to have high levels of pH, which will eventually reduce with nitrification process by an established bacteria colony.
Balancing pH in Aquaponics
The pH level of your aquaponics system can be tricky to balance, especially if your system is still relatively new and has not been fully established. Fish, bacteria, and plants do not agree when it comes to the perfect pH reading.
Fish and bacteria tend to thrive in slightly alkaline conditions, while plants prefer to be on the acidic side. For this reason, balancing pH should be an important focus in aquaponics. To reach that desired balance or at least, make a compromise for all the organisms in your system, you need to target a neutral range.
A pH level of 7 is neutral, but giving a little bit of adjustment on both sides, such that you’ll arrive at a range of 6.8 to 7.2, will be fine for your system.
Risks of Poor pH Management in Aquaponics
Outside of the ideal pH range will not be detrimental to the health of your system. Prolonged exposure to poor pH management, however, can have significant impacts on either one of the organisms in your system.
pH can affect the availability of nutrients and the plants’ capacity to absorb these nutrients. This means pH can have an effect on plant growth. Ideally, plants will absorb the needed nutrients when the pH is around 6.5 to 7.5. Note that some vegetables prefer it to be a little more acidic, such as lettuce and eggplants.
Meanwhile, fish used in aquaponic systems often prefer a more alkaline environment. For example, tilapia can thrive better in pH 7 to 9. At the same time, nitrifying bacteria – which converts fish waste to plant food – can perform their roles very well in pH levels of 8 to 9.
If the right pH is not met for the bacteria, they can’t adequately process ammonia from fish waste in the water. The nitrifying process comes to a halt and water then becomes too toxic for fish to thrive.
To get the right balance, testing your pH is essential and should be done at least once a week. In the next section, we will discuss how pH levels in Aquaponics are tested.
How To Test pH in Aquaponics
pH levels in your system can be measured in two ways: using pH test strips or using a digital pH meter. pH test strips are usually the least expensive option, but they produce less accurate results. They do come in handy when used for educational purposes in a classroom setting.
pH readings will be based on a color scale, which can be subjective. It could mislead you to think that you already have too high or too low a reading, which may prompt you to take unnecessary steps to amend the pH.
To get a more accurate result, aquaponics practitioners prefer to use a pH meter. It may cost more, but it’s worth the investment since you’ll be using it to maintain the system. A pH meter is most useful in a large-scale commercial aquaponics system, but home aquaponic practitioners can benefit from them as well.
Accuracy of a pH Meter
The precision and accuracy of your chosen pH meter will depend on how well you calibrate it. You might go for the more recognized and advanced brands, but if you don’t know how to calibrate the device well, it will be useless. Meanwhile, if you diligently calibrate your pH meter, the lower-tech pH meters will suffice.
Generally, going for high-quality pH meters will give you more precise readings. For this reason, you want to invest in high-quality but not necessarily expensive pH meters to avoid problems of inaccurate and imprecise pH readings.
With a plethora of options, it can be challenging to choose the best one that suits your needs. Below are some of the best pH meters we recommend for your setup.
Best pH Meters for Aquaponics
Below are some of the best pH meters we recommend for your setup. We also included quick information about ease of use and other features to get an idea of the different options available when shopping.
Bluelab pH – is considered one of the best pH meters to use in Aquaponics. This combo unit measures both pH and water temperature that are displayed on a backlit-LCD display for easy reading. It has an auto-off function to conserve battery power and a low-battery warning to tell you it’s time to change batteries.
Since it’s portable, this compact device provides your pH reading quickly and conveniently to ensure your crops will always have maximum absorption of nutrients. The only downside to this device is that it doesn’t come with a calibration solution, which means you need to shell out more for its maintenance.
- Ease of Use: easy, fast; temperature and pH reading on an LCD
- Features: fully waterproof; with sponge cap to keep probe moist
Milwaukee (MW) 100 pH Meter
Milwaukee 100 – is a portable pH meter with removable and replaceable probes for ease of maintenance and storage. It is also available as MW 101, which measures both temperature and pH.
But unlike BlueLab pHPen, MW 100 comes with a calibration solution to ensure your device will always be in good condition. Not only does MW100 provide fast and reliable measurements, but it is also easy to operate. Just dip the probe into your water sample or tank and wait until the numbers have stabilized.
- Ease of Use: lightweight and portable, LCD screen; includes calibration solution
- Features: ergonomic light design, long battery life
Apera Instruments pocket pH meter
Apera Instruments – is also considered one of the premium brands of pH meters out there. The AI311 model comes with a complete easy calibration kit and a high-quality glass probe. The 3-Color LED window lets you see accurate results clearly. Plus, it helps you identify the different modes of operation, such as the display of temperature and pH, when calibrations are completed, and when pH reading is stabilized.
This device is already considered pricey, and the replacement probes can set you back more. But with proper use of this device, it can last a long time, and it will be worth the investment.
- Ease of Use: LED screen, easy calibration
- Features: replaceable glass probe, fully waterproof
Hanna Instruments HI 9813-6N pH/EC/TDS
Hanna Instruments – measures more than pH and temperature, as it also reads electroconductivity (EC) and total dissolved solids (TDS). With these features, it can be an ideal device for large-scale Aquaponics.
What’s great about this combo pH meter is that it has a built-in calibration reminder to help you remember the important step in maintaining a pH meter, which is regular calibration.
- Ease of Use: easy calibration, easy to read display
- Features: waterproof, built-in calibration reminder
Billiony Digital pH meter
When it comes to more affordable options that don’t compromise the accuracy of readings, Billiony Digital pH meter can be a decent choice. This will be all you need if you’re not looking for an exact reading, but rather a range.
If you’re just starting out with Aquaponics with an indoor setup and growing only a few varieties of crops, then going for this affordable but reliable device will suffice.
- Ease of Use: fits in the pocket, produces reasonably good readings
- Features: built-in temperature compensation
How To Choose a pH Meter for Aquaponics
Even if you’re presented with pertinent details of a pH meter, you might still have a hard time choosing which brand or type to go for. It all boils down to the following factors:
- Price – are you willing to invest in high-quality, expensive instruments, or do you simply want to settle for one that’s cheap yet functional? If you have the available resources, then the high-quality premium pH meters will be a great option. If not, you can always have the cheaper one that has the function that you need.
- Intended usage – Are you a novice at Aquaponics? Or do you have an established commercial system that needs a new pH meter? For simple setups, going for a portable pocket pH meter is acceptable. For a more accurate and precise reading needed in commercial setups, a more technologically advanced choice will be better.
- Accuracy and precision – Some aquaponics practitioners don’t need much of an exact reading from a pH meter but only a reading of an acceptable range. If you want an exact measurement, it only makes sense to go for a more premium device.
Maintaining a balance in water pH is critical to the overall function of your aquaponics system. Every organism in your system has its own ideal pH range, but to be on the safe side, the best pH for Aquaponics is typically around 6.8 and 7.2.
To achieve such balance, make sure to check on your pH levels regularly as fluctuations can easily shock your environment, bringing negative impacts to your crops, fish, and bacteria. That said, investing in a quality pH tester that provides reliable, accurate results can largely benefit your system.