How to Lower PPM in Hydroponics in 4 Easy Steps

One of the most important terminologies to understand in the hydroponic world is PPM (Parts Per Million). The accuracy of this measurement ultimately controls the overall growth of the plant.

The PPM must be checked regularly to ensure the solution is balanced.

If the PPM is too low, the plants won’t receive enough food, stunting their growth. That’s why it’s important to learn how to lower ppm in hydroponics so that we can tackle the issue when need be.

In fact, a PPM that is too high will also overfeed the plants, causing a buildup of salts around the roots. If left unattended, the plant will dry out and slowly die.

How to Lower ppm in hydroponics

Correcting this issue by adding some fresh water with the right pH is possible. We will go into that in more detail soon. For now, though, let’s look at all things PPM and how it all works. 

What does ppm stand for?

PPM is a measurement of concentration. It’s defined as the number of milligrams of soluble minerals (Ca, Mg, P, K, S, Na), crude protein, and total digestible nutrients per liter of water.

In layman’s terms, it’s the strength of the solution in the hydroponic reservoir.

Each plant has an optimal PPM tolerance. When the nutrients are distributed correctly, it enables them to grow efficiently.

A general tolerance level is between 800 and 1500 ppm. Furthermore, each plant requires a specific PPM for each growth cycle stage. 

What is a good water ppm For Hydroponics?

As mentioned earlier, each plant requires a specific PPM to optimize its growth.

To go one step further, though, the PPM needs to be adjusted according to each phase of the growing cycle they are presently in. Let’s have a look at the different stages and PPM’s required

What is a good water ppm For Hydroponics
  • Early growth stage (350 to 400 PPM – Minimal nutrients are added during this stage which gives almost no reading
  • Seedlings (400 to 500 PPM) – As starter nutrients are added, the numbers slowly rise. 
  • Early vegging (650 to 750 PPM) – This is generally when you begin to transplant and won’t use much in the way of extra nutrients. 
  • Mid-stage vegging (750 to 800 PPM) – The numbers begin to rise more rapidly from here as more nutrients are slowly added. 
  • Late stage vegging (850 to 900 PPM) – Another sharp rise in nutrients as the plants get ready to flower. 
  • Early flowering (900 to 950 PPM) – Again, an uptick in nutrients as the flowers crave more food to begin producing bearing stems and leaves. 
  • Mid-stage flowering (950 to 1100 PPM) – Even more nutrients are required as the plant strengthens its stem, leaves and flowers. 
  • Late stage flowering (1100 to 1150 PPM) – The last nutrient push is during this stage. Especially to maximize all areas of the plant’s growth as it begins to bear produce.
  • Flower End/Flushing (0 to 400 PPM) – Complete flush of any remaining nutrients as the cycle ends. No nutrients are added here. The reading drops dramatically as the flush occurs. 

What PPM is too high for hydroponics?

Each plant requires a specific PPM for whatever stage of the growing cycle that they are currently in.

This means that if the PPM is too high for that particular plant during that particular stage of its growing cycle, issues will begin to start popping up. Generally, the plant roots will begin to form salt deposits around them.

If left this way for too long, the plants will dry out from dehydration and die. It is recommended that you maintain the PPM between 800-1500 if you are unsure about the plant that you are growing.

Most plants grow better between TDS levels of 600 – 1000, so 800 is their sweet spot. Generally, any higher than 1500 is considered too high.

How to Lower ppm in Hydroponics?

Maintaining an evenly balanced PPM is a little tricky in the beginning. Things can be thrown out of whack if they aren’t monitored correctly.

It is possible to install reverse osmosis into your system; they can remove particles as small as ions.

If you don’t have that luxury and the PPM starts to creep that little bit too high, there are some other simple adjustments that you can make to lower it in a controlled manner.

Firstly, you can check the levels using a truncheon meter. Once you take an initial reading, there are a few different paths that you can go down. These include:

How to Lower ppm in Hydroponics (step by step)

Step 1: Diagnose the root cause

Working out what’s causing the issue is always the first thing that should be done. A couple of factors can cause the PPM of a hydroponic system to rise. 

For example:

  • Too much fertilizer may have been added to the system 
  • Using water with a high pH value
  • Using tap water instead of distilled
  • Nutrients accumulation around the roots
  • Inadequate oxygenation.

Step 2: Use a Carbon Filter

The best and most thorough type of carbon filter is reverse osmosis. They effectively eliminate bad minerals such as chloramine and chlorine from the water and lower the water’s hardness by helping remove larger pre-dissolved materials.

They are one of the most heavy-duty water filters you can purchase for your system.

Step 3: Add Some Fresh water

If your hydroponic system is a little smaller, you can add fresh, distilled water with the correct pH level to help dilute the solution. Quite often, PPM can be lowered by counteracting the pH level.

Simply test the water, mix in some freshwater, and then test again.

Step 4: Add more plants to the system

Again, this is ideal with a smaller system. It’s possible to add more plants into your system (if space isn’t an option). The more plants there are, the extra sets of roots can soak up the more solutions.

As a result, the PPM will drop.

How to Measure PPM in Hydroponics?

The easiest way to test and measure the PPM of your hydroponics system is by using a TDS meter. This measures the total amount of dissolved solids (TDS). Once you test a few times, it’s pretty simple to understand.

How to Measure PPM in Hydroponics

For example, if you get a reading of 100 PPM from 1,000,000 particles, 100 of those particles are dissolved ions. The remaining 999,900 are water molecules. 100 PPM is at the low end of the spectrum. 

You don’t need anything fancy to test the TDS; here are a couple of the best easy-to-use products:

How do we identify if the ppm is high for hydroponics?

Generally, the best way to control the PPM of your hydroponics system is by using a TDS water tester. They are extremely accurate and require little knowledge to understand them.

However, if you haven’t made the appropriate checks in a while, you may notice excessive amounts of salt building up around the roots of your plants.

This is usually caused by too many nutrients or even poor quality water. It mostly stems from the plants being overfed by fertilizer, and the salts remain unused.

It can be harmful to the plants if untreated. However, the issue can be resolved by adding some clean, distilled water.

How to maintain an ideal ppm level in hydroponics?

The only way to ensure your PPM levels is by using a TDS meter. This will measure the exact amount at that time. Additionally, you want to monitor the levels as you make changes.

Routine checks must be made in case any short, sharp spikes occur, damaging the plants without noticing.

How to maintain an ideal ppm level in hydroponics

Additionally, all environmental conditions for the plants should be met. These include using the right types of growing medium, using clean, distilled water, adding in the right amount of fertilizers and flushing the system regularly.

This will ensure the levels are maintained and clean the system out, preventing things such as algae and pest infestations from forming. 

Frequently Asked Questions (fAQs)

Will boiling water lower ppm?

Although boiling water can make tap water microbiologically safe by killing microorganisms, it won’t remove harmful substances such as chlorine and/or lead from tap water. Therefore it will not be able to lower the PPM of the water. If anything, it may raise the PPM. It’s best to just use clean, distilled water as all of these additives can safely be filtered and removed.

How often should hydroponic water be changed?

When filling a nutrient reservoir in a hydroponic system, you generally only fill it up to a certain level. Each time you top the water up, the water rises. Once the water has been topped up so much that the reservoir is full, you should change out the system’s water. An average-sized system would generally need a changeover every 2-3 weeks.

Is 2000 ppm too high?

It all depends on the type of plant and the stage of the cycle in which they are growing. For some plants, 2000 PPM will burn them out; for others, they may thrive. There is no universally recommended PPM, although the sweet spot for most plants is around the 800 mark.


As we have discovered, balancing the PPM is crucial to growing using a hydroponic system. Different plants require different amounts of nutrients, affecting the PPM depending on their needs.

The best thing to do is purchase a good quality TDS meter and understand how it works.

The rest is just fine-tuning! We hope that this article on how to lower ppm in hydroponics has helped you understand the intricacies of lowering the PPM value of your hydroponic system.

Thanks for tuning in, and as always, happy growing!

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