Targeted control of algae in the hydroponic system

## Introduction

Algae in hydroponic systems can contaminate the reservoir, impair the flow of nutrients and reduce the oxygen content of the water. Unlike in soil-based growing systems, where the organic content is often higher, hydroponic growers must pay particular attention to hygiene and correct environmental conditions. This guide explains how algae infestation in hydroponic systems can be detected at an early stage, how it can be prevented and how it can be combated in an emergency.

## Causes and detection

Algae thrive primarily under the following conditions:

- **Light incidence in the reservoir:** Light-transmitting or opaquely placed reservoirs promote algae growth.

- Warmth:** Temperatures above 22°C favor growth, while the ideal temperature window for hydroponics is between 18-22°C.

- Excess nutrients:** An unregulated nutrient supply and stagnant water provide ideal conditions.

**Diagnosis:** Algae infestations typically show green or brown film formations on the inner walls of the reservoir and in the tubes. In addition, finely divided deposits may be visible, which impair the oxygen exchange at the heat exchanger.

## Preventive measures

The best way to combat algae is to prevent it. The following steps should be implemented in the hydroponic system:

### 1. darkening of the reservoir

Use opaque or colored reservoirs to minimize light penetration. If transparent reservoirs are used, an opaque cover (e.g. aluminum foil or special covers) can help.

### 2. regular cleaning

A cleaner reservoir reduces the nutrient residues that serve as food for algae. Clean the reservoir and hoses at least once a week, ideally during a system check. Remove the toughest algae residues mechanically with non-toxic brushes.

### 3. check the water parameters

Always keep the pH value within the target range of 5.5-6.0 to ensure optimum nutrient uptake and less nutrient residue. The electrical conductivity (EC value) should also be checked and adjusted regularly. Pay attention to the following points:

- **pH:** A pH value that is too high can lead to nutrient deposits that promote algae.

- EC:** Checking this is essential, as high EC values can provide excess nutrients.

- Temperature:** Keep the water temperature between 18 and 22°C to create an ideal environment.

### 4. oxygen supply

A good oxygen supply prevents the formation of biofilms. Use aeration systems that ensure a continuous supply of oxygen to the roots without mixing the reservoir if this could lead to algae formation.

## Control measures in the event of an infestation

If an algae infestation occurs despite preventive measures, the following steps are recommended:

### Mechanical removal

- Vacuuming and brushing:** First remove the algae film manually. Use soft brushes and a water extractor to remove the deposits from the reservoir, hoses and surface.

- Filter replacement:** If filters are installed in your system, check them and replace them if they are clogged with algae residue.

### Gentle chemical treatment

If the infestation is severe, the targeted use of diluted hydrogen peroxide (H₂O₂) can help. Please note the following:

- **Dosage:** Use a low concentration (3% H₂O₂) and dose precisely so as not to damage the roots.

- Application:** Carry out an application test in the reservoir and observe the plant reaction. Rapid oxidation reduces algae infestation without disturbing the system in the long term.

### Adjustment of the environmental conditions

- **Check the lighting conditions:** Ensure that no unwanted light enters the reservoir.

- **Water change:** A partial or complete water change can help to remove excess algae spores and renew the nutrient solution.

## Monitoring and aftercare

After control, you should monitor the system closely. Check regularly:

- The reservoir and supply lines for new algae residues

- The water parameters (pH, EC, temperature) for deviations

- The function of the aeration to ensure a good oxygen supply

Rely on a regular hygiene concept that integrates both preventive and reactive measures. Consistent documentation of the water parameters and cleaning dates helps to draw conclusions about the cause and to be able to react more quickly in the event of future algae infestation.

## Summary

Algae in hydroponic systems is an often underestimated pest that is favored by insufficient darkening, inadequate cleaning and uncontrolled water parameters. Suitable preventive measures - opaque reservoirs, regular cleaning, strict control of pH, EC and temperature as well as a good oxygen supply - can effectively prevent algae infestation. If an infestation occurs, mechanical removal and, if necessary, targeted treatment with diluted H₂O₂ show good results. Continuous monitoring of the system ensures healthy roots in the long term and maximizes the yield in hydroponic cultivation.

**Note:** Any chemical treatment should be done carefully and in consultation with the specific needs of your plants. Regular checks and small adjustments are the key to a successful hydroponic system without algae problems.

## Pro Tips

- Use opaque reservoirs

- Clean the system regularly and document the cleaning intervals

- Check pH, EC and temperature weekly

- Avoid unnecessary incidence of light in the reservoir

- For heavy infestations, use gentle oxidizing agents such as H₂O₂ in low doses