Aqua Ultraviolet – Best Water to Give A Cannabis Plant

Water is crucial for the growth of cannabis plants, just like any other plant. However, the quality of water matters. Why? Because the wrong pH level or temperature hinders nutrient absorption by the roots, making it vital to provide the best water for the cannabis plant.

So, how can you determine the ideal water composition for nurturing cannabis plants? Let’s explore that now!

Optimal Water Quality

When grown hydroponically, cannabis plants prefer a pH of 5.5–6.5; but in soil, they prefer a pH of 6–6.8. Proving the best pH water for cannabis enhances nutrient absorption by the roots, ensuring the effective uptake of various nutrients at different levels.

Measuring the ppm in the water before using it to water cannabis plants

Wisconsin-based commercial cultivator, Kurt Kinneman, mentions that soil pH can be closer to 7 without causing plants to struggle to absorb nutrients since it acts as a plant buffer. (MG Magazine, 2022)

Given that water is the primary means of nutrient delivery for root absorption, the mineral content of the water is also crucial. Water composition is measured as parts per million, or ppm. Ideally, in the seedling and early vegetative phases, it must be 500 to 600ppm; in the late vegetative stage, 800 to 900ppm and throughout the blossoming period, 1000 to 1100ppm. (Grow Light Info, 2022)

The water must also be between 68 and 73 degrees Fahrenheit for optimal growth.

Water Choices

Rain Water:

Rainwater is often pH neutral and has high PPM values for cannabis. If your area receives a lot of precipitation, this is an inexpensive and long-term option. However, excessive levels of atmospheric pollutants result in rainfall becoming highly acidic. Before putting it on crops, collect a sample in a bucket and test the pH level.

Spring Water:

If you’ve heard the term ‘spring water,’ it refers to groundwater, which varies depending on where you live. So test it and make any necessary adjustments before feeding this water to your plants.


Watering a cannabis plant in a bucket with a watering hose

Tap Water:

Most US states add chlorine to drinking water to eliminate dangerous germs and bacteria, however, high chlorine level results in nutrient lockout and stunted growth.

So, you can leave tap water in the sun for a day to allow the chlorine to dissipate. But, if that isn’t an option, a chemical solution, like sodium sulfate, will do the job. If your water is treated with chloramines instead of chlorine or the chlorine is used with fluoride, you must use the best water filter for cannabis – specifically designed to remove these substances.

Bottled Water:

Bottled water is a fantastic alternative if your area has exceptionally high PPMs or fluoride levels. However, the cost quickly adds up. Otherwise, it has the same quality as tap water.

Distilled Water:

If you can afford it, use distilled water and complement them with nutrients. Since this water has zero nutrients, you can control any nutrient additions. But remember that nutrient-free water will suck up all the good nutrients your plants require to thrive.

A marijuana leaf with dry, brown edges caused by nutrient burn

Nutrient Burn

Nutrient burn occurs when cannabis plants are exposed to excessive nutrients, adversely affecting their health and growth. Unfortunately, since plants can’t eliminate the excess nutrients, they suffer from root and leaf damage.

Generally speaking – depending on the circumstances – cannabis plants have a fair probability of recovering. Gently remove all the damaged parts, i.e., broken leaves, dead flowers, and foliage. And flush your growing medium as soon as possible with fresh, pH-balanced water.

If you are growing in a reservoir, check the pH and EC levels of the water and make any necessary adjustments with fresh water. (Royal Queen Seeds, 2021).

For optimum growth and health of your cannabis plants, ensuring they receive the highest quality water is essential. AquaUV offers top-of-the-line UV Water Sterilizer Solutions harnessing the power of Advanced Ultraviolet Technologies.

From landscape water management to cannabis cultivation, consider us your go-to solution provider trusted by professionals in the cannabis industry. Explore our extensive collection today!


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For over three decades, Aqua Ultraviolet has been the premier manufacturer of ultraviolet sterilizers and bio-mechanical filtration.

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