Growing cannabis is an amazing process of nurturing a seed into a fully grown specimen that is burdened only by large and heavy buds. The reward for cultivating the herb is massive, yet the process is not without its challenges. Growers are in a constant battle between ensuring their crop has the correct amount of nutrients, light, air and water, and defending it against possible threats, such as mould, mildew and invading insects.

One such threat comes in the form of algae. If you notice a green layer occurring around your cannabis crop, you may be looking at it. It’s best to try and prevent the formation of algae and to remove it as soon as it is detected. Left untreated, it may hinder the growth and yield of your plants.

Algae can occur in different forms from multicellular organisms like seaweed to unicellular, microscopic organisms. Algae thrives in warm water, especially where there is a good amount of light and nutrients present. This combination is the ideal setting for these lifeforms to make themselves at home within hydroponic and aeroponic systems. In this case, the algae may begin to spread and even clog up crucial tubing. If they proliferate enough, the lifeforms could start to compromise the health of your cannabis plants by preventing the roots from being able to utilise oxygen.

During the day, algae absorb carbon dioxide and release oxygen; at night, they release carbon dioxide and absorb oxygen. This pattern allows the algae to suck up most of the oxygen in a hydroponic system, cutting off the vital supply to your plants.

Algae algas cannabis cultivation


Before we cover how to prevent and remove this issue, it is worth learning how to identify the problem in the first place. Plus, the algae won’t be given the opportunity to do much damage if you catch them early on in their attempted crusade. Although mostly green, algae can also appear brown, gold, red and black. Be sure to look out for these colours floating around in reservoirs or clinging onto pipes and tubing. If you have a filter in your system, be sure to check it for any signs of algae accumulation.

In addition to its visual symptoms, algae may also result in a pungent scent. If you notice an unusually earthy or mouldy smell around your system, algae may be forming.


One of the best preventative measures when it comes to algae growth is blocking its light source. Light is one of the main components of the process of photosynthesis, which all plants require in order to create the energy they need to survive.

The key is to use opaque equipment when building an aeroponic or hydroponic setup. In other words, use a system that does not allow any light to penetrate wet areas or regions where water is stored, such as the reservoir. Cutting off the light source will hinder or totally eliminate growth. If you have already invested in equipment that is slightly transparent and lets light through, you can always cover it using foil or another type of light blocking material.

Some hydroponic systems use clay balls as a growing medium, which helps to block light and serves as a support for the base of the plants. If you are using a different type of growing medium that might harbour algae growth, be sure to take measures to cover this too.

cannabis algae hydroponics aeroponics


Regular cleaning of your system equipment will help to defend against algae growth. Adding a small amount of hydrogen peroxide to the reservoir may boost oxygen supplies to the roots of your plants and hinder algae growth.

Keep things moving with a pump or a filter system. Algae seem to prefer still-standing and stagnant water, so keeping your water supply flowing may help to prevent growth and subsequent spread.


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