How To Adjust Hydroponic PH (My Experience)

The pH level of your hydroponic solution can have a huge effect on whether the plants thrive or wither. If your nutrient solution is too acidic or alkaline for your crop, you’ll see problems like nutrient lockout, nutrient deficiencies and burned roots. 

An appropriate pH level will help prevent these issues from occurring and help your plant grow into robust, healthy vegetation that can produce fruit or flowers efficiently.

How to raise pH in Hydroponics – Avoid this mistake
Understanding the importance of pH balance in hydroponics
How to add nutrients to a hydroponic system
Step-by-step instructions for building a hydroponic system
Tips for raising pH levels in hydroponics
Methods for lowering pH levels in hydroponics
Preventing and managing root rot in hydroponics
Further reading recommendations for hydroponics pH and adjustment
Frequently asked questions about hydroponics pH

Use A Test Kit

pH testing is the best way to ensure your nutrient solution maintains a proper pH for optimal plant growth. 

Test kits can be expensive and inaccurate, but it may be worth it if you’re growing out multiple plants at once and want to keep them all in the same nutrient solution. If you want to test your pH without buying a kit, there are several ways you can do so:

  • Use litmus paper (can be purchased at any drug store)
  • Use a TDS meter (a digital device used for measuring dissolved solids in water)

When growing plants using a hydroponic system, it’s vital to ensure they receive the necessary nutrients to promote healthy growth. Check out our guide on adding nutrients to a hydroponic system to learn more about the types of nutrients your plants need and how to administer them effectively.

Control Your Water Ph Before You Add Nutrients

When it comes to adjusting the pH, there are two main goals:

  • Keep your water at a pH between 5.5 and 6.5
  • Don’t let your pH drop below 5.0 or rise above 7.0

To test the current pH of your hydroponic reservoir, use an electronic tester or a liquid test kit that can be purchased at most gardening stores. 

To adjust your water’s acidity level, add a solution of phosphoric acid to raise it; calcium carbonate (lime) is used to lower it. 

The amount required will depend on how much you need to change things by – as little as half-a-teaspoon per gallon up to one cup per ten gallons may be all that’s needed depending on how low or high you want the new reading to be after adding these additives

Use Buffers And Acid Blends

You can use a buffer to keep your pH stable. A buffer is a chemical that prevents the release of too much acid or alkali, thereby maintaining an appropriate pH level.

A buffer solution is created by mixing an acid blend with an alkaline solution. The acidic component of the blend releases hydronium ions into the water and neutralizes any excess hydrogen ions that would otherwise cause a drop in pH levels if you didn’t have it on hand. 

Acid blends can be purchased from your local hydroponic store or online, but you’ll need a pH meter (see below) to make sure they’re doing their job!

If you’re new to hydroponics, building a hydroponic system might seem overwhelming. However, with the right guidance, it can be done successfully. Check out our guide on how to build a hydroponic system for step-by-step instructions on creating your own hydroponic garden.

Use Sodium Carbonate

Sodium carbonate (soda ash) is a white powder and can be found in home improvement stores or online. It is also known as washing soda, which makes sense considering its main use is to wash clothes.

Sodium carbonate has a very high pH which makes it great for raising the pH level of water when you’re growing hydroponic plants.

It’s important to note that sodium carbonate can also be used to neutralize acids as well as remove stains from clothing!

Add Calcium Carbonate

If you need to raise your nutrient solution’s pH, then you can use calcium carbonate to do so. Add one part calcium carbonate powder to four parts water, and stir well. 

The amount of acidity in your nutrient solution will be reduced by adding this chemical. It’s important that you don’t add too much calcium carbonate at once; otherwise, it could cause an imbalance in your nutrient solution’s pH levels. 

You should also make sure that the ratio of calcium carbonate to water is equalized before adding it slowly into your hydroponic system or aquarium otherwise, it may not dissolve completely and cause clogging problems down the line.

It may take a few days for the pH levels in your hydroponic system or aquarium to stabilize after adding any type of new chemical like this; however long it takes depends on how acidic or alkaline your water already was before adding them (or if there was already some form of buffer present). 

In general though: if your plants are growing well but seem unhappy about having less sunlight than usual (they’re growing slower), then try increasing their CO2 injection rate instead!

Controlling the pH level of your hydroponic solution is essential for maintaining healthy plant growth. If you’re struggling to increase the pH level, check out our guide on bringing pH up in hydroponics for tips and tricks on how to achieve a balanced pH level.

Use Sodium Bicarbonate

If you’re trying to raise the pH of your hydroponic solution, use sodium bicarbonate. This is because it’s a weak base. 

It will raise the pH of your solution and not cause it to become too alkaline. It’s not as strong a base as potassium hydroxide, so you don’t have to worry about making your solution too alkaline if you add some slowly.

Add Potassium Carbonate

To lower the pH of your water, add potassium carbonate. This is a salt that you can add in any amount to adjust the acidity of your water. In fact, it’s a safe and effective way to lower pH!

If your plants are not getting enough nutrients and are showing signs of deficiency (such as yellow leaves), it’s possible that you’re using fertilizer with too much phosphorus for the plants’ needs. You should look for fertilizer that has more nitrogen than phosphorus.

Conversely, if your hydroponic solution’s pH level is too high, it can harm your plants. Check out our guide on bringing pH down in hydroponics to learn about the different ways to lower the pH level in hydroponics and keep your plants thriving.

Use Potassium Hydroxide

Potassium hydroxide (KOH) is a weak base that can be used to raise the pH of your nutrient solution. It is also suitable for using as an adjuster in hydroponic solutions, especially if you need to lower the pH.

Potassium hydroxide has a pH of 13 at room temperature, but it will become less soluble in water at higher temperatures:

Add Potassium Phosphate

Potassium phosphate is another way to raise the pH. It’s also a good source of potassium, so it can help maintain your plants’ chlorophyll production as well.

Because potassium phosphate builds up in the soil over time, it should only be used sparingly and only if you have a test kit. When adding this product, make sure to follow these instructions:

  • Use one part potassium phosphate per ten parts water
  • Don’t use more than 20 ml (1 tbs) per gallon of water (or 4 ml/liter).

Root rot is a common problem in hydroponic gardening and can significantly affect plant health. If you’re having issues with root rot, check out our guide on avoiding root rot in hydroponics for tips on detecting and preventing root rot from occurring in your hydroponic system.

Use Magnesium Oxide Or Calcium Oxide

If you’re using a pH test kit that measures whole numbers, you’ll want to use magnesium oxide or calcium oxide. 

These compounds will raise the pH by one unit, so if your solution is at 6 and the ideal range is 5 to 6, add enough of these compounds until it reads 7. 

Then test again in an hour or two just to see how much it’s changed since then—it may be better now at 7 than it was before when it was at 6!

Use this same technique for lowering the pH: if your solution reads 8 but needs to be between 7 and 8 (for example), use 1/2 cup of either compound per gallon of water until it reaches 7; then check again in an hour or two and adjust accordingly.

Tips for Using Magnesium Oxide or Calcium Oxide to Adjust pH

Tips & Tricks
Determine the current pH level of your hydroponic solution using a pH test kit that measures whole numbers
Choose the appropriate supplement, either calcium oxide or magnesium oxide, based on your current pH level and your desired pH level
Add the supplement to the hydroponic solution slowly, stirring it thoroughly in to ensure even distribution
Wait for approximately 30 minutes before retesting the pH level, as it takes some time for the supplement to take effect
Repeat the process as needed, adding small amounts of the supplement at a time until you achieve the desired pH level

Use Phosphoric Acid

The pH of the nutrient solution can be lowered by adding phosphoric acid. This is a weak acid that’s safe for use in hydroponic systems and soil fertilizers. Phosphoric acid lowers the pH by increasing hydrogen ions in solution, which increases acidity.

To lower your nutrient solution’s pH with phosphoric acid, measure out 25 ml per gallon of water being used, then add it to your irrigation system.

Lower Ph With Sulfuric Acid Or Hydrochloric Acid

If you’re working with sulfuric acid, be sure to wear gloves and goggles. If you get the chemical on your skin, it can cause burns. Sulfuric acid is also a strong oxidizer it reacts with metal and other materials to release oxygen. 

This means that if you spill any of the liquid in this process, it may react with any metal objects in its path and burn them (including wires).

It’s important to note that hydrochloric acid works as well as sulfuric acid but is less dangerous: it has no oxidizing properties and will not cause burns when spilled on bare skin (though you should still wear gloves).

Tips for Lowering pH Safely With Sulfuric Acid or Hydrochloric Acid

Safety Measures
Wear protective gear including gloves and goggles to avoid skin and eye contact
Work with the acid in a well-ventilated area to avoid inhalation of harmful fumes
Add the acid to water slowly in small amounts, never the other way around, to prevent overheating and splashing
Keep a neutralizing agent, such as baking soda, nearby in case of spills or splashes
Avoid contact with metals, as sulfuric acid reacts with them to release oxygen and can lead to dangerous chemical reactions
Store sulfuric acid or hydrochloric acid in a cool, dry, and secure location away from incompatible materials and sources of heat or ignition

Add Sulfuric Acid Cautiously To Avoid Burns

In addition to being a strong acid, sulfuric acid can irritate the skin and eyes. If you get it on your bare hands, it may burn them.

If you spill some on yourself or in the eyes, flush with water immediately. Wear protective eyewear and gloves when handling sulfuric acid to avoid getting any on you.

Tips for Safely Using Sulfuric Acid

Safety Measures
Wear protective gloves, goggles and clothing to prevent skin and eye irritation
Work in a well-ventilated area to prevent inhalation of fumes
Add sulfuric acid slowly and cautiously to water, never the other way around, to prevent splashing and overheating
Keep a neutralizing agent, such as baking soda, nearby to neutralize any spills or splashes
Store sulfuric acid in a secure, cool location, away from incompatible materials such as organic combustibles


Now that you know the basics of how to adjust your hydroponic pH, you can get started on your next grow. 

Just remember to follow these tips and keep an eye on your water as it changes throughout the growing cycle. If you’re still unsure about any of these methods for adjusting your pH, don’t hesitate to reach out for help!

Further Reading

Plantophiles: PH Up and Down in Hydroponics: A comprehensive guide on the importance of pH balance in hydroponics and how to manage it using pH up and down solutions.

University of Washington: Adjusting pH in Hydroponic Systems: A research paper detailing various methods of adjusting pH in hydroponic systems, including the use of various chemicals and pH buffers.

Your Indoor Herbs: Best pH Hydroponics Monitor & Adjust: A review of the best pH hydroponics monitor and adjust tools available on the market, with recommendations for various budgets and needs.


What is pH in hydroponics?

The pH scale measures how acidic or alkaline a liquid is on a scale from 0-14. In hydroponics, pH refers to the acidity/alkalinity level of the nutrient solution provided to plants.

Why is pH balance important in hydroponics?

The pH level of a hydroponic nutrient solution determines how readily plants can absorb essential nutrients. If the pH level is too high or low, the nutrients can become unavailable to plants, leading to nutrient deficiencies and stunted growth.

How do you adjust pH levels in hydroponics?

pH levels in hydroponics can be adjusted through the use of pH up and down solutions, or by using natural methods such as adding dolomite lime or vinegar to the nutrient solution.

How often should you check pH levels in hydroponics?

It’s recommended to check pH levels daily in hydroponics to ensure that the nutrient solution is within the optimal range for plant growth.

What is the optimal pH range for hydroponics?

The optimal pH range for hydroponics is typically between 5.5-6.5, although the appropriate range may vary depending on the specific plants being grown.