Turf & Rec

Features Agronomy
Getting ahead of algae problems in ponds

June 14, 2016  By  Mike Jiggens

By Julia Webber

The spring has brought many problems for pond owners this year with an abundance of algae and other problems quickly getting ahead of us. 

During the mild winter there was very little algae die-off, not only because of the warmer temperatures but also due to a lack of snow cover on top of the ice to cut sunlight to the algae.  Once the ice melted, our ponds revealed that they had been slowly growing algae all winter long.  This problem was only made more difficult by the large fluctuations in temperature this spring, which made it difficult for ponds to become balanced with beneficial bacteria to help ease the problem.


So that brings us to a question: what could have been done to prevent the problems that we experienced this spring?  
Like many challenges of the superintendent and owner, preventative measures that could have avoided these problems must have taken place long before the problem even existed. This requires a level of planning and foresight that can be difficult in the busy summer season when you are facing a myriad of other challenges. In the long run, preventative maintenance will save you both time and money.  Additionally, preventative maintenance will require you to deal with fewer unexpected problems.

One of the main preventative maintenance measures is the use of beneficial bacteria to balance  the pond and compete with algae and pond weeds for resources. Similarly to the way good bacteria in yogurt and probiotics can help your digestion, beneficial bacteria can make pond maintenance run more smoothly. Bacteria is specialized, and should therefore be chosen for your pond’s specific situation.


The pond industry has come a long way with beneficial bacteria in the last decade. From its roots of waste water bacteria, companies have developed many unique strains of bacteria for pond-specific applications. Most notably for Canadians, there has even been the development of formulations for low or high water temperatures, as well as targeting different sources of nutrients. In order to find the right product for your pond, we will explore some of the variables you should be considering.

Firstly, in order for beneficial bacteria to work most effectively and for you to see results, your pond will require an abundant, consistent supply of oxygen. This means that you should be aerating your pond to encourage circulation, oxygenate, and reap the most benefits of the bacteria additives.  

This can be accomplished through the use of an oil-free air compressor feeding air stones and/or a fountain. There are benefits to each of these types of aeration but for the purpose of managing pond nutrients with beneficial bacteria, the most ideal would be an oil-free continuous-duty air compressor providing air to diffusers located on the bottom.

Air diffusers (air stones) on the bottom of the pond break the air up into small bubbles that diffuse easily into the water as well as drag water upwards with the rising column, promoting circulation. A properly-sized aeration system will have the benefit of providing oxygen evenly throughout the pond top to bottom as well as side to side. This means that there will be abundant oxygen for beneficial bacteria to do their work as well as good circulation in the pond to evenly distribute the bacteria to make them more effective.

This brings us to the second point: how to distribute the bacteria evenly into your pond. Beneficial bacteria needs to be distributed at the source of the problem. To this end, manufacturers have developed beneficial bacteria in a variety of formats to help with distribution and application ease.

Beneficial bacteria are available in liquids, solupacks (powder format in a water-soluble package), and pellets. Each of these formats have advantages and disadvantages, but the manufacturers often choose the format based on the goal of the bacteria.

Liquids are best distributed by spraying them over the surface of the pond to provide even distribution and mixing for action throughout the water column. These formulations are most often general water column treatments but can be nutrient-specific. Liquid bacteria are also often more active and can produce faster results, but are more diluted in solution as the bacteria need to have food available.  

Solupacks are very useful for distributing bacteria over large bodies of water. These soluble packs can be tossed in from around the shoreline or from a boat and allowed to dissolve as they drift. They are a highly concentrated, freeze-dried bacteria, so there is less product required for a given area than would be required if using a liquid. This can dramatically save on time for applying the product.

Since they are freeze dried, the bacteria are in a semi-dormant state that allows them to be more tightly packed. Once they come into contact with water they are reactivated. This format is generally used for bacteria intended to treat the whole water body and most often intended for nutrients suspended within the water column.

Pellets are the last main format of beneficial bacteria. Generally a pelletized version of freeze-dried bacteria, pellets are specifically designed to sink to the bottom. This format is easy to distribute either in a boat-mounted spreader, hand spreader or simply by hand distribution.  

These pellets have the advantage that they can be placed in targeted areas. Over time they will dissolve, activate and begin to move around but generally they are going to act on the closest nutrient source. Manufactures often use this format when trying to target bottom sludge. Bottom sludge can be a main nutrient source for your whole pond as it often accumulates more quickly than it can be used up.  

This bottom sludge is made up of years of dead leaves, grass clippings, branches as well as past pond algae and weeds that have died off. As it accumulates, it blocks lower layers from access to oxygen, which causes these layers to break down anaerobically (without oxygen). Anaerobic breakdown is not only much slower then aerobic (with oxygen) breakdown, but it produces by-products with undesirable smells, such as sulphur dioxide (rotten egg smell). Introducing aeration and beneficial bacteria can change this breakdown process to aerobic breakdown, speeding the process and encouraging optimal pond health.  

When choosing a format and formulation of bacteria, you will need to consider what kind of problem that you are trying to prevent. This luckily does not require a crystal ball, but it does require you to think back to the problems you’ve had in the past. If your main problem was bottom-rooted weeds last summer, that is likely the problem you will have this summer.  

Bottom-rooted weeds are able to grow for two main reasons: an abundant source of nutrients (bottom sludge) and access to sunlight. This is why weed growth is worst in shallow ponds or around the edge of deeper ponds. By accelerating the breakdown of bottom sludge you can remove the nutrient source for these weeds and work to prevent this problem from occurring. If there are minimal nutrients on the bottom to feed the roots, there will be less plant growth. This would work similarly to removing all the topsoil prior to sodding an area. The grass will not grow well without the nutrients that it needs. If you have a 20-year-old pond that has never seen aeration or bacteria, there will be a lot of organic material to break down before you reach your goal of a crisp, bare bottom. Starting now will be moving in the right direction and will continuously improve the situation, instead of the pond weeds growing progressively worse every year.

This brings us to last consideration when choosing a beneficial bacteria, and that is water temperature. Bacteria formulations all have ideal operating temperatures; in general, the warmer the water, the faster the bacteria grow and work to a point. In the past, the available beneficial bacteria were only effective above 15 degrees Celsius, and so there were very few months in a Canadian season for them to be effective, especially in a season like this year with fluctuating temperatures.  

Very recently, manufacturers have developed better strains of bacteria, and some particular to a wider range of temperatures. Products are available that work as low as 5 degrees Celsius, which could add a few months of nutrient breakdown to every season in Ontario. By targeting the right temperature range with your choice of bacteria, you can see more effect each season and reach your cleanup goals sooner.  

There are a lot of products on the market to help make the ponds on your property look their best. Beneficial bacteria—although not the fastest—will solve the root of the problem by actually cleaning up the water and bottom sludge. Finding the right product for your pond is important, and to that end I hope that this article will help you. Every pond is unique, and I would encourage you to talk with a pond professional in your area to help take some of the mystery out of these products.

Julia Webber is president of Fish Farm Supply Co.; http://fishfarmsupply.ca ; julia@fishfarmsupply.ca

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