Balancing Nutrients and Chemicals in Dams

Dam Water Chemistry Analysis

Having the correct nutrient levels in your water are important for ensuring long-term water quality. Without getting our science on too much, today we discuss, the expected nutrient levels generally expected for a dam.

First of all, it is important to understand that the source of water in your dam determines your water quality nutrient levels. Rainwater from your roof will be less nutrient rich than water captured by run-off, as this water can contain nearly anything including solids, chemicals and even living organisms.

Why should I be worried about dam nutrient imbalances?

Your waterbody is connected to the environment that surrounds it, and so it is vital to be mindful of the water inputs (what water is coming into the dam) and outputs (what is coming out of your waterbody). Water chemistry and nutrient levels are also highly important for applications in aquaculture, horticulture, hydroponics and aquaponics where the nutrients and chemicals are highly controlled and balanced. In your dam, it is very difficult to control what is going into your water and imbalances can occur without warning. This is an issue because an imbalance such as high levels of nitrogen or phosphorus can influence how much aquatic weed, algae and sludge exists.

If the nutrient levels become majorly skewed, they can lead to fish kills, animal deaths or even a visit from the EPA.

Ideal water nutrient balance

The nutrients and chemicals of most importance are nitrogen, ammonia, phosphorus, salinity and pH.

  • Salinity: Dissolved salts that are present in the water. This can be measured through the Electrical conductivity (EC) as a direct measure of the ions in the water and is usually measured in MicroSiemens per centimetre where the higher the value, the higher the salt content. The ideal EC level is difficult to determine as it is also influenced by temperature, however generally speaking the EC levels should be between 0-88 MicroSiemens per centimetre for human consumption. Between 800-2,500 MicroSiemens per centimetre is expected for water used mostly for watering livestock and irrigation. Any higher than this is not recommended for human consumption or irrigation
  • pH: Is the measure of acidity and alkalinity of water. We expect the water to be neutral (between 6.5-8.5) with <6 being more acidic and >8 being more alkaline.
    For a deeper analysis, visit our blog on pH.
  • Phosphorus: The ideal range is between 0.005 – 0.05 milligrams per litre
  • Nitrogen: The ideal range is between 0.1 – 0.5 milligrams per litre

What common dam nutrient imbalances look like

Large outbreaks of algae, aquatic weed and sludge are a key visual indicator that there is excess nutrient in the water.
Fish kills are also a major indicator that there is something very wrong with the chemical balance of your water.

How to control nutrient imbalances in my dam

In most cases, nutrients are stored in the sludge layers that accumulate. If the sludge is treated, then this will reduce the nutrient levels and help to minimise the occurrences of aquatic weed, algae and sludge. It is important that there is oxygen readily available and this is why aeration is equally important and works hand-in-hand with biological treatments.

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