Controlling Algae in Your Pond

There are two types of algae to be concerned about in your decorative pond. The first is suspended algae which is a free floating algae that causes your pond to turn the greenish colour often referred to as pea soup. The second type of algae is string algae which creates longer hair like strands that form in clumps. This algae is the type that plagues pond owners once it gets warmer. Often it seems like it comes out of nowhere overnight.
In reality there are several reasons for the algae to grow the way it does, and there are several easy to carry out steps that will help control it so that it never bothers you again.

The first and most important step to getting better water clarity and reducing algae is a working filtration system. Many times people have a pond with a pump in the centre of it that has a plastic and foam “filter” attached to it. This is not a true filter, but rather a debris strainer. It helps to keep anything from getting stuck in the pump but it does very little to filtering the pond.

` Ideally, a filter should have two components to it, mechanical filtration and biological filtration. The mechanical filtration is a series of foam or media that the dirty water has to flow through, leaving behind the floating particulates as it goes. This helps to remove the suspended algae as it gets cleaned through the mechanical filter. The biological filter helps to colonize beneficial bacteria which, in turn, helps to control floating and string algae. The beneficial bacteria break down sludge, nitrites and ammonia and this helps to control the algae in your pond.

A filtration system works hand in hand with the pump used to recycle water within the pond. It is important that the pump and filter be the right size for each other and that they work together properly. In addition to this it is also important that the pump recycle enough water to clean the right amount of water per hour. The general rule is that you should recycle the water in your pond at least once every two hours, or as often as once an hour. This helps to ensure the water is filtered properly.

Once the proper filter/pump arrangement is in place, the next step is to ensure that there is a good colony of beneficial bacteria. Bacteria can be easily added to your pond in either a liquid or a powder form. They need warmer temperatures to live and become active so they should be added to your pond every spring once the water temperature reaches a minimum of 50°-60°. More of the bacteria would be added in the spring and early summer while the pond is just getting started, with regular doses being given later on throughout the season when the water temperature has increased.
Beneficial bacteria are needed to help break down sludge, ammonia and nitrites. This all in turn helps to keep the pond free of algae. Sludge is organic material that collects at the bottom of the pond over time. This organic material can come from many sources and by using bacteria it is broken down over a period of time. Bacteria will not eliminate all sludge from the bottom of the pond, and in some cases it needs to be cleaned out or physically removed.
A good way to diminish the amount of sludge and organic material collecting at the bottom of your pond is to use a skimmer system which helps to prevent organic material from collecting on the bottom of the pond. Skimmers are a main filtration component in swimming pools and have only recently become more popular in garden ponds. They are very easy to retrofit to a pre-existent pond and if used in conjunction with a biological waterfalls filter which is also easy to retrofit, they provide the most efficient and natural looking filtration system possible.

If you have a large amount of floating particles in your pond, be it either floating algae or other particles, you can also use a flocculant to help clump together the particles so that they are large enough to get caught by the filtration system. There are two types of flocculants, one used for inorganic debris, and another used for organic material. I prefer to use a product that clumps together both types of particles, so that both problems are taken care of.

There are several other steps that you can use to help maintain a healthy pond ecosystem.
 Do not overfeed your fish. Fish are not like us and do not need three square meals a day. A good pond ecosystem will support the fish and they will need little feeding. In the extreme heat you can reduce your feeding schedule to three or four time a week at most. Fish should only be feed enough food at each feeding that they can eat within a few minutes. You do not want the food to break down in the water and add to the nutrient base that will feed algae.
 Do not overstock your pond with fish. Generally speaking your pond should have no more than 1” of fish length per square foot of pond surface. The more fish you have the more waste is excreted into the water increasing your ammonia in the water, which in turn will increase the nitrite and nitrate balance, causing the algae to grow more. It is better to have the right amount of fish and a healthy clear pond than to have too many fish and not be able to see them.
 Do not drain and refill your pond regularly. The goal is to create a balance in your pond that will support an ecosystem, which will not happen if the water is removed on a regular basis. If you have to do this to see the bottom of your pond, the filtration system and pond balance are not working together. This is a common problem and often a reason why people get turned off of water features. It is possible to fix these problems and we are happy to help you do so.
 Never use an algaecide in your pond. This makes your pond chemical dependant and makes it extremely hard to develop an ecosystem. While it seems to help the pond immediately, in the end it makes the job of owning a pond more difficult. It is much better to institute a proper filtration system with the use of beneficial bacteria than to dose your pond with an algaecide.
 Do not use pesticides or fertilizers close to the pond or allow them to runoff into the pond. This will upset the balance in your pond and make it more difficult to keep in a healthy state.
 Add beneficial bacteria on a regular basis. This bacteria does a wonderful job at eating up the excess nutrients that cause problems in your pond. They are an organic and healthy part of your pond that are not dangerous or toxic to your, your fish or to plants in any way. Bacteria are a constant source of balance to your pond.
 Keep plants in your pond. There are a large selection of plants that help your pond in various ways. Mix up the varieties so that you have marginal plants, oxygenators, floating plants, water lilies and other deeper plants. Plants are a very healthy part of your pond and they help to detoxify your pond and add oxygen. Keep in mind, there is a little maintenance to them, but very little for the benefit they offer your pond.
 Attend one of our seminars on ponds. We are here to help you build your backyard paradise.

Don’t be afraid to dive into water gardening. If done properly, it is less work per square foot than maintaining a lawn once it is installed. The enjoyment and attraction of water in your backyard is indescribable, and is so easy to do that you can be enjoying your water garden in no time. Come in and see one of your water feature specialists and let us help you develop the lifestyle that you’ve been missing.

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