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PPM For Growing Cannabis

Understanding water quality may make the difference between a beginner and a professional cannabis producer. If you have planted or at least learned about weed cultivation, you may encounter the phrase PPM. What is PPM for cannabis? Is it necessary for your crop?

If you want to become a real cannabis planter, don’t miss this feature. This article will inform you of all the necessary knowledge regarding the PPM. We also include some tips for choosing a high-quality water source for your cultivation. 

Let’s read on to discover!

What Is PPM?

Parts Per Million (PPM) is an abbreviation for parts per million. It’s a metric that indicates how many metals, minerals, and other compounds are present in a given content of water. 

When gardeners mention PPM, they’re referring to the TDS (Total Dissolved Solids) level in the water they’re feeding their crops.

For instance, if there are 3 pounds of marijuana in 1,000,000 lbs of water, it means the marijuana concentration is 3 PPM. 

The PPB unit of measure, which refers to “parts per billion,” is equivalent in concept.

What Is A TDS Meter?

A TDS Meter is a device that estimates PPM levels. TDS meters come in a variety of costs and functions. Some even feature temperature sensors and some hold buttons. Some can work with a larger range of PPM.

what is a TDS meter
We use the TDS meter to measure the PPM levels

Those considering buying a TDS meter need to be aware that the PPM range a specific meter detects should not be the key factor. Most TDS meters can come close to 5000 PPM, while others may detect up to 9999 PPM. However, you’ll rarely find anything higher than 3500 PPM in marijuana production.

In reality, the maximum PPM allowed in any of the Standard Hydroponic systems is 1500 PPM. So, you don’t need to employ a meter that can measure up to that peak. 

What Is An EC Meter?

An EC meter measures the Electrical Conductivity in the water. You can use this reading to calculate the total amount of solubles in the water.

Then you may be wondering the difference between the EC meter and the TDS meter, right? 

Regarding cannabis cultivation, their difference is minor. Many TDS meters detect the electric conductivity of substances. Then, they convert the data to PPM. To put it another way, the TDS meters are EC meters.

what is an EC meter
A TDS and an EC meter can be one

S/m is a unit of measurement for electrical conductivity. However, because we’re working with such a limited scale, results will appear as μS or millisiemens/meter.

While EC meters perform similarly to TDS meters, you only need to get one. Most feeding sources and charts of data on the water quality will provide readings in PPM. 

The conversion of EC meter values (mS/m) to PPM is quite simple. However, the correct unit of measurement will help you save lots of time and effort.

Why Is Measuring PPM For Growing Cannabis?

When growing marijuana, whether or not you need a TDS meter relies on the water system and your production purposes. 

To optimize yield, commercial companies should keep a careful eye on it. The selection for the private grower is dependent on how committed the gardener is to improve his growing procedures and to master his or her skill.

It is critical to measure the nutrient and salt levels in the water. The measurement helps make sure the content of nutrients for your plants. 

important measuring PPM
It’s important to know nutrient and salt levels in the water

For example, on the first day, you check the PPM one day and receive a figure of 1,600 PPM, for example. On the following day, check your PPM and obtain a result of 2,100 PPM. Then, you’re well aware that you overdid it with the nutrients on the previous day.

Many marijuana farmers have produced and collected a huge number of sticky and dank plants. These same planters can create excellent buds without bothering about CO2 levels in the grow space.

It’s a good idea to use sophisticated procedures if you want your crop to be as fine and fruitful as possible. Learn about the PPM if you ever want to achieve high-quality crops. As a consequence, you’ll be a more informed and successful farmer!

How To Measure PPM?

Always begin by blending in the fertilizers and then modifying the pH. After that, verify the PPM of the mixture. You should carry out this step before watering your plants. It would be best if you kept the record for future reference.

You only have to test your runoff’s PPM every month. However, some gardeners check it more often to ensure nutrient quality.

how to measure PPM
Testing the runoff every month is necessary

Here is how you measure the PPM:

  • Set your TDS meter after calibrating it, ensure it displays zero. Then, place it in the liquid you plan to test. The result may be from 0 to 10 PPM if you’re using the osmosis water, which is mineral-free.
  • If you’re working with tap water, the normal result in the EU is somewhere from 50 to 300 PPM.
  • If the water contains more than 500 PPM, you must take action. It can prevent your cannabis from absorbing nutrients. 

Soil runoff will have a significantly higher PPM reading than coco. Since soil comes from many distinct components, the overall measure will increase. The high value, in this case, does not indicate that the soil has been over-fertilized.

When evaluating PPM in the soil runoff, you’re searching for trends rather than the sufficient number of nutrients in your soil. You shouldn’t worry about substantial changes in the results.

The Desirable Range For PPM

desirable range for PPM
Different stages in cannabis life cycle require different PPM level

Marijuana plants’ nutritional requirements change with time: 

  • Seedlings require only clean water and no fertilizers.
  • Vegging stage: Your plants need water with a PPM from 400 to 800 during the first section of this stage. In the second half of the stage, the plants require more, from 800 to 1000 PPM.
  • The flowering stage: Planters should adjust the PPM to reach 1400 to 1600 in this phase.
  • Harvest stage: In the final stage, planters may decrease the PPM down to 0 to 600. This indicator helps in the preparation of your harvest.

How To Adjust The PPM?

Cannabis plants will grow if you know what PPM levels are best for them. They can absorb nutrients more efficiently and avoid nutritional burns. If the PPM level is not correct, you still have some methods to fix it.

1. The PPM Is Lower Than In The Runoff

It’s optimal to have a low PPM runoff result when compared to the nutrient’s PPM value. Keep track of the PPM levels periodically to ensure the major reductions. 

Your plants are continuously receiving the same quantity of nutrients if the PPM lowers from 1500 to 800 for a whole week. Consider slowly raising your fertilizer treatment rates if the runoff levels are really low.

The PPM is lower than in the runoff
If the PPM level is not appropriate, you need to adjust

2. The PPM Remains The Same

The problem may arise if there is no variation in PPM findings between your runoff and nutrients. This figure indicates that your plants aren’t obtaining enough nutrients. 

If there is such a thing in your crop, have a look at the pH levels. Unbalanced pH levels might make it hard to absorb nutrients. Phosphate and nitrate, for example, absorb better at particular pH levels.

3. The PPM Is Too Low

If the reservoir shows lower-than-normal PPM values, you are missing nutrients because of the nutrient lockout. You need to examine your nutrient storage for the white precipitate construct. 

When certain ions don’t combine properly and create a solid, the white construct can emerge. This reaction is especially true with calcium phosphate.

To avoid this problem, ensure you’re correctly blending your nutrients when you apply them. You also need to wash the mixing cup somewhere in between.

4. The PPM Is Higher Than The Runoff

Although the too high PPM measurement from your runoff is uncommon, it suggests a salt accumulation at the root system. The accumulation gets trapped and degrades slowly into the runoff. The trapping accumulation results in high PPM rates. 

You can remove the calcium salt accumulation by using a line cleaning or by flushing it with water.

Tips Water Quality For Growing Cannabis

Water with excellent quality is an essential component in the cultivation of high-grade marijuana. The water can also greatly affect the PPM. 

On the other hand, low-quality water can significantly harm your plant’s growth and capacity to produce high-quality flowers.

Water Quality For Growing Cannabis
The water source is crucial for cannabis development

There are some options for the most effective water source as follows.

Water Filtration

Although there are a variety of filtering options currently, marijuana producers often choose a RO (reverse osmosis) device. 

The main benefit of the water filtration method is that it allows an endless clean water supply. Moreover, for large-scale water purification, RO systems appear to be the safest and cleanest option. However, most farmers may worry about the initial investment required to set up the system.


Rainwater is usually pure and clean, which makes it ideal for hydroponics. This water source, on the other hand, may not be as pure as most people believe due to industrial pollutants. Furthermore, acquiring and using it might be a pain.

A water collecting system is generally necessary in this case. Rain catchers come in a variety of sizes, styles, and materials. Some of them are more pricey and complex to construct and operate.

However, there are some other models that you can make at home with readily accessible components. Moreover, the majority of these methods need relatively little effort and time to maintain.

Some water filtering systems can gather recycled and unpolluted water from nearby suppliers. 

Some governments, on the other hand, have opted to ban or restrict the collecting of gray water. As a result, before purchasing in a rainwater collection setup, double-check if storing rainwater is legal in your region or not.

The key to cultivating properly with rainwater is to check it before use, just like you would with the tap water. Mineral contents and pH levels may need to be modified.

Distilled Water

Distilled water is an ideal source of clean and pure water, particularly for tiny plants. You may feel confident that distilled water doesn’t need any additional filtration. 

You can easily find this water source at the local groceries. However, while a bottle of distilled water may appear to be affordable at first, the expense adds up quickly. 

Furthermore, some growers believe that filtered tap source is equally as clean as bottled water. As a result, distilled water will not be suitable for big crops or budget-conscious farmers.

Unpurified Tap Water

One of the most widely available sources of water for cannabis growing is unfiltered tap water. This supplier is both cheap and simple to obtain. And, contrary to common belief, it isn’t all that awful for the plants.

The purity of tap water, on the other hand, varies by municipality. Certain places’ tap water may have more pollutants than others. The tap water often contains chlorine and calcium. These chemicals won’t attack the plants. However, they can have a significant impact on their biological processes.

Always analyze the tap water before using it. You’ll know precisely what’s inside. Moreover, you could also be able to formulate a filtering method.


Getting to know about PPM for cannabis brings you lots of benefits. It helps detect harmful issues for your plants. Thanks to the information, you can adjust the nutritional quantity for your plants to flourish. 

Hopefully, you can manage the PPM figure for the best cultivation.

If you have any questions, please feel free to ask. Thank you for reading!

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