Dissolved Oxygen

Dissolved oxygen is the amount of oxygen present in water or nutrient solution, usually measured in mg/L or as percent saturation. Roots need oxygen for respiration, energy production, and active nutrient uptake.

In indoor growing systems, dissolved oxygen is especially important in reservoirs, deep water culture, aeroponics, recirculating irrigation, and saturated substrates. Oxygen levels fall as water temperature rises, as roots and microbes consume oxygen, or when water is poorly mixed.

Ways to improve dissolved oxygen:

• Keep nutrient solution within the intended temperature range
• Use air stones, venturi injectors, waterfalls, or circulation pumps
• Avoid stagnant reservoirs and dead zones in plumbing
• Prevent excessive organic buildup in tanks and lines
• Maintain enough dryback or air-filled porosity in substrates

Low dissolved oxygen can reduce root performance even when EC and pH are correct. It is best evaluated with root zone temperature, water movement, root appearance, and overall plant response.