Algal blooms - What the experts say

Details

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The Cause 

Water movement, or rather the lack of it, together with higher temperatures experienced during the warmer months are likely to be of more importance in determining the onset of algal blooms rather than nutrient levels.

“Whilst nutrient pollution, i.e. Phosphorus in waterways exacerbate the growth of algal blooms, there is little unequivocal evidence to support the view that most algal blooms are caused by excessive nutrient pollution. It is possible to argue that the key to determinant in the onset of an algal bloom is the physical mixing rather than nutrient status of the water body”.

“Calm water conditions combined with temperature stratification around the warmer months of the year provide a catalyst for algal blooms.  The nutrient status of the water enables the bloom to grow quicker but not necessarily is a reduced nutrient status going to minimise the bloom size, just slow down the reproduction. (Sainty & Jacobs. 1994).

“Well mixed waters reduce the release of nutrients from the sediments and disperse nuisance algal blooms. Also the use of aerators promotes the growth of the biologically friendly aquatic fauna which compete against the algae." (Entwistle, Sonnerman & Lewis 1997).

The Solution

The installation of re-circulators such as The Rio and Brio Systems which provide flow and de-stratification, and the aerator/circulators such as The EOLO and Force 7, both of which not only provide flow but also utilise the Venturi principle to introduce huge volumes of air into the aerator slipstream, providing greatly improved oxygenation.

Furthermore, all the above mentioned being of the submerged motor type, they are capable of being submerged at varying depths from close to the surface, where they can also help with de-gassing, to up to five metres depth so as to further intensify the beneficial effects of aeration, de-stratification and circulation.

Since submerged motor aerators and re-circulators of this type are inconspicuous as well as being silent in operation, they are particularly well suited to rod and line fisheries where they do not in any way detract from the enjoyment of both the sport and the tranquillity of the environment.

It is important to remember when treating any algal bloom or weed problem that the dead and decaying matter will consume oxygen during the rotting process. The decaying plant matter can often deplete a water of available dissolved oxygen, possibly leading to large scale fish mortalities.

It is best to focus on preventative measures, such as addressing the organic silt, which can often be the source of the algal problem. Aeration and possibly treatments such as Calcium Carbonate and liquid barley straw extract can bring about positive results. Ultrasonic units are a relatively new way of dealing with nuisance algae, and can prove very effective. To discuss the use of calcium carbonate or ultrasonic algae devices please This email address is being protected from spambots. You need JavaScript enabled to view it.

Where additional degassing as well as the introduction of oxygen is required, the Splash aerator is an excellent machine. The Splash, which throws up a dome of white water of around two cubic metres of water per minute in the half hp version and over three cubic metres of water a minute in the one hp version, can provide both a very efficient and low cost answer to many problems.

The new 1.5hp Splash provides roughly the same aeration and de-stratification effect but with the added appeal of a higher throw of water in an attractive fountain effect which may be a bonus to those who wish to have a feature lake such as hotel fisheries, caravan parks and landscaped gardens.

For deeper waters, the Splash can have an extended water draw skirt fitted so as to intensify the de-stratifying and degassing effects by bringing up colder water from close to the bottom, aerating it and releasing unwanted gasses formed by rotting vegetation and other nutrients locked in the pond bottom.

In the winter months the lifting of water from the bottom can be very useful in helping to keep fishing lakes ice free since the then warmer water is brought to the surface thus helping offset the freezing surface temperature.

None of the above aerators need necessarily break the bank since costs vary from around £575 +VAT for a Splash aerator and around £675 + VAT for a Force 7 aerator. Remember we have discounts available for fisheries & fishing club members of the Angling Trust

All of the above aerators and more are available from us here at Aquaculture Equipment and our distributors throughout the United Kingdom and the Republic of Ireland who can offer everything from help and advice, both of which come free of charge, to a complete installation package and full after sales service.

For further details, literature and a free product CD showing the working aerators above and below the water, please This email address is being protected from spambots. You need JavaScript enabled to view it.