Algae and aquatic plants thrive in nutrient rich conditions. High levels of phosphorus and fixed nitrogen can lead to heavy algae blooms and weed growth.
Fixed nitrogen (ammonia, nitrites and nitrates) can be effectively mitigated utilizing aeration and bioaugmentation. Phosphorus (phosphates) is more challenging to mitigate because it does not enter the atmosphere. Once phosphorus enters a lake or pond, it continually leaches upward out of the sediments and is utilized by plants and algae that reside in the water column. Human activity has drastically increased the rate at which phosphorus has accumulated in our lakes, ponds and rivers.
Best Management Practices
Watershed phosphorus runoff can be limited by implementing best management practices that reduce or eliminate phosphorus from entering the pond. Examples of this would be limiting livestock access to a waterbody, planting native vegetation near the shoreline, or restricting fertilizer use on nearby lawns. Even the most rigid management practices are unlikely to reduce elevated, external phosphorus to natural levels.
There are a number substances that will absorb phosphate, immobilizing it and making it biologically unavailable. They are known as phosphorus precipitants. Some of them can be effectively used to lower phosphorus concentrations in lakes, reservoirs and ponds.
Which product to use?
Algae Control Canada has a number of products that can easily and safely applied. As these products can be cost prohibitive for larger applications, we only recommend them for smaller water bodies.
For most ponds, lakes and industrial water bodies we recommend using aluminum based products (alum and sodium aluminate) and having our Water Quality Specialists handle the application.
When properly applied, it is effective, reliable, food grade product which is affordable and safe. Alum has been used to mitigate phosphorus since the late 1960s, and is used in drinking water treatment facilities worldwide as a clarifier.
Water Column Stripping
Phosphorus precipitants, also called flocculants, can be used to “strip” phosphorus in a water column before it becomes available to be absorbed by algae or plants. An appropriate dose of the flocculant is applied to the water. It absorbs the phosphorus in the water column and precipitates to the bottom.
Algae Control Canada’s On-Shore Application System is used to “intercept” external sources of phosphorus (for example, agricultural runoff entering from a ditch or culvert). With this approach, the chemical formulation is injected into the external water source and binds the phosphorus to the alum before it enters the lake, thus inactivating the phosphorus making it unavailable for algal growth.
If there is an accumulated amount of bioavailable phosphorus in the sediments of a water body, it will continually re-enter the water column through natural lake processes, such as “turnover”, “stratification” and through periods of low dissolved oxygen which occur near the bottom of the lake. This phosphorus often leads to toxic algae blooms, and green scums on the surface of the lake. A properly calculated dose and application of alum can effectively “inactivate” phosphorus for years or decades.
For larger lakes (50 acres or larger) and industrial applications we are pleased to offer full comprehensive alum services, including:
- pre-project water quality monitoring,
- algae identification,
- chemical dose determination,
- GPS-guided chemical application,
- alum injection systems for the treatment of storm water/stream water, and
- post-project water quality monitoring and evaluation.
Contact us today and one of our Water Quality Specialists will help you determine which of our phosphorus management products and services are right for you.