pH Control

What is pH?

pH measures the acidity or alkalinity of any given solution. pH stands for potential of hydrogen, indicating the hydrogen ions in the solution.

pH is measured on a scale from 0 to 14; 7 is neutral, under 7 is acidic and over 7 is basic.

Why is pH Important in Cannabis?

Every nutrient and micronutrient is absorbed when the solution your giving your cannabis plants is within a certain pH range. This means that even if you’re using the right amount of nutrients and they’re high in quality, your cannabis plants won’t be able to absorb nutrients if the liquid they’re delivered in doesn’t have the right pH level.

The correct pH range can also vary depending on the substrate used. You can establish the perfect pH by making sure to check your growing characteristics. These are the perfect pH levels for each type of substrate:

Soil: the pH in your nutrient solution should be somewhere between 6.4 to 7.
In coco coir and hydroponic grows, the pH value can be between 5.5 and 6.5.

During the growth stage you should use the lowest pH levels recommended, which favours nitrogen absorption.

During the flowering period, you should choose the highest recommended levels for phosphorus absorption.

How to Measure pH

As we were saying above, measuring pH is an incredibly important process in order to grow successful cannabis plants, especially when it comes to indoor growing. There are different tools that can be used to measure pH.

pH Reactive Meter

The GHE pH Reactive Meter is super easy to use:

Fill a dropper halfway (included in the kit) and add some drops of reactive liquid.
Depending on the colour, you’ll know the pH level by comparing it to the included colour card.

This is the cheapest method. However, it’s not very precise if used with fertilizers that can change the colour of your nutrient solution.

pH-meter or Digital pH Meter

This device works by measuring the voltage between two electrodes, one of which is sensitive to high concentrations of hydrogen ions. Digital pH meters offer precise readings. They’re more expensive than reactive kits and require maintenance, but provide much better results.

pH-related Cannabis Issues

There may not be much of a difference at the start – your plants will keep growing normally.
As they grow, they won’t be able to absorb certain types of nutrients.
After a few days you’ll start seeing signed of nutrient deficiencies. These signs will be visible in plant leaves and growth, which will have stopped.
Many growers tend to increase nutrients once this start to happen, but this is actually a massive mistake.
Nutrients build up in the substrate when plants can’t absorb them, causing nutrient blockage which can make the situation even worse.

How to Get Rid of Nutrient Blockage in Substrates

If you come to find yourself in this situation, you can get rid of nutrient blockage by flushing your plants’ roots.

In order to do this, you need to use plenty of pH controlled water. You’ll need to use three times as much water as the capacity of your flowerpots – for example, a 7L pot needs about 21L of water. You’ll need to allow the water to drain out fully and then use low amounts of nutrients when watering next.

The most affordable and eco-friendly option is to use a cleaner, that can be mixed in with your water when feeding your plants. Allow 10% of the water to drain out and then use small amounts of nutrients.

Once your plants have recovered using this technique, we highly recommend using enzymes.

How to Lower pH Levels

If you notice that your pH is too high after measuring it, you need to reduce it using a pH reducing product, generally known as pH- or pH Down.

Our catalogue has pH products that contain:

Phosphoric acid: such as pH- by Bio Nova.
Citric acid: including pH+ by BioBizz, Lemon Kick by Plagron or Trabe’s Citric Acid.
Citric and phosphoric acid: pH- by Terra Aquatica.
Nitric acid: pH- by Hy-Pro.

You also have the option of using a solid pH product for water tanks such as pH- Powder by Terra Aquatica.

How to Increase pH Value

In order to increase pH in your water when it’s too acidic, you’ll need to use pH increasers such as pH+ by Terra Aquatica, pH+ by Bio Nova or pH+ by BioBizz.