pH meters and cannabis cultivation

The key to successful cannabis growing lies in proper plant nutrition. It's true that every environmental factor should be adequately laid down in order to maximize the outcome of your crop: air exchange, type of lighting, temperature, humidity, etc. However, it would be pointless to choose a complete and balanced range of fertilizers if you are not taking into account the pH of the nutrient solution, or in other words, the acidity or alkalinity level in the feed you are giving to your plants.

To ensure proper nutrient uptake through the plant's root system, each macro and micronutrient in the marijuana feed must be administered with regard to a particular acidity value (pH), otherwise the absorption won't be adequate. This factor is very important to make the most of the fertilizers and to prevent nutrient deficiencies and overfeeding problems, thus obtaining a bountiful harvest.

What is pH?

As already mentioned in our article on pH and marijuana, pH is the degree of acidity or alkalinity of a substance. Maintaining a proper pH value in the nutrient solution is therefore vital to achieve the maximum absorption of the elements you are feeding to your plants, which will provide them with everything they need for an explosive growth. Let's see some of the most popular pH meters for cannabis growers, as well as the liquids needed to change (raise or lower) a solution's pH. Bear in mind that the optimal pH value for hydroponic and coco coir setups is usually between 5.5 and 6.2, and slightly higher (between 6 and 7) when growing in soil.

Manual PH meters

Let's start with the cheapest option, GHE's liquid pH meter. It's very simple to use: all you have to do is fill the small test tube halfway with nutrient solution, and add 3 drops of the reactive liquid. Almost immediately, the liquid inside the test tube will turn a certain color, which you'll have to compare with the included chart. This way, you'll learn the approximate pH value of the nutrient solution, and know if you need to adjust it.

Although easy and economical, the previous method is not as accurate as digital pH meters, as is the case of the basic Milwaukee pH meter. To use it, you just need to turn it on and immerse the probe located at the lower end of the meter in the nutrient solution. Within seconds, the reading will stabilize itself and give you the pH value. As you'll see soon, this type of meters should be calibrated every few weeks to ensure readings as accurate as possible.

Another more comprehensive option is the Milwaukee waterproof pH meter. Splash-resistant and with an operational autonomy of 1500 hours of use, it's a portable pH meter of professional level which also measures the water temperature. Both the probe and the electrode are replaceable, so you won't have to buy a new meter in case of breakage or failure.

Continuous pH meters

This type of meters is characterized for always having the probe submerged in the tank or nutrient solution reservoir, so you can check the pH value at any time with a quick glance at its digital display. A good example is the Milwaukee continuous pH meter, which includes automatic temperature compensation, 2-point manual calibration, probe with 2m cable (replaceable), and visual LED alarm.

The most professional option is, without a doubt, the Milwaukee continuous pH meter with dosing pump, a great device that allows you to not only learn the pH value, but also adjust it automatically with the dosing pump included. All you have to do is connect the pump to a liquid reservoir to lower the pH, and the meter itself will adjust the pH to the chosen value, saving you the cumbersome job of adding a pH Down liquid till you get the desired value.

Products to adjust pH values

Once you have a reliable reading, and this doesn’t match what you expect, you'll need to raise or lower the pH value in order to ensure proper plant nutrition. This is generally achieved by using an acid element to lower the pH level, or an alkaline one to raise it. To lower it, you can use GHE's pH reducers in both powder and liquid form, being the latter the most popular, or GHE's Hesi pH reducer (available for both growing and flowering phases).

On the other hand, if you want to raise the nutrient solution's pH (something that tends to occur much less frequently), you also have several options, such as GHE pH Up and Hesi pH Plus boosters.

Accessories for pH meters maintenance

Finally, we also offer everything you need for a proper maintenance of your pH meter, so you can always rely on the readings. The digital meters must be calibrated on a regular basis to ensure correct operation, something that can be achieved with pH 4.01 and pH 7.01 calibration buffer solutions. Each meter comes with instructions on how to perform this operation, which is really simple.

It is also recommended to use a pH probe cleaning solution after each measurement, so the probe is completely clean and ready for another use, free of debris that could alter the next reading. In addition, and especially if you are not using the meter for a while, it's advisable to use a pH probe storage solution to maintain the probe moist and ready to use.

As you can see, controlling and adjusting the pH of the nutrient solution is easier than it may seem at first glance. Basically, you only need a meter to know the pH value, and a reducer to adjust it to the desired level. Feel free to leave here your questions or comments!

Happy growing!