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before aeration	Lake & Pond Aeration control of algae | water quality  | pollution   aeration homepage  | destratification of lakes | Installation of air diffusers   useful equipment, wireless oxygen & temp controller  click here		after aeration
Over view		Dulwich Park London lagoon effluent treatment landfill leachate
Natural habitats, lakes, ponds storm water basins and lagoon type effluent treatment plants  are coming under increasing pressure from the public as an amenity or recreational value, and by industry as a means of water treatment.  In case where the system are new,  the biology will need help in order to become established.  In more mature systems,  the ability of the ecosystem to cope with the demands placed upon the ecology of the water body can be too great for the system to self sustain especially if there is nutrient run-off or a pollution load.  Under these conditions there will be excessive algal blooms and the water may go anaerobic, there will be fish kills, or the water will look unsightly and will start to smell. Blue green algae blooms may develop which will make the water toxic to animals and humans.  These systems all need help,  but this help should be carefully balanced to provide the greatest benefit for the least amount of effort,  with the system focused on helping nature to support the extra demands.  The net results are an un-obtrusive system,   greatly improved water quality, better environment for the aquatic organisms with a greater species diversity, and much better aesthetic and amenity value for the public. A similar approach is used for the treatment of grossly polluted lakes or lagoons, or as a means of effluent treatment. It is possible to treat the waste water to a very high standard to allow it to be discharged to surface water, or to be recycled as grey water or irrigation water See landfill leachate aeration systems  click here
How does it work The first stage is always aeration of the water.  Dryden Aqua manufacture a very fine bubble air diffusers that has its own internal ballast.  The diffusers are semi flexible tube type diffuser that have the best of ceramic diffusers and membrane diffuser but without the disadvantages.  see diffuser section  Air is past through the diffusers and as the fine diffusion cloud of air pass up through the water,  the air bubbles drag water behind, this has the affect of moving huge amounts of water. See section on destratification click here  The aeration system will dissolved oxygen into the water,   one diffusers code 6.2.10 diffusing 10 cubm/hr of air will add at least 25 kw oxygen to the water which is sufficient to support  up to 2000 kg of fish.  The air diffusers will also support the growth of aerobic bacteria  ( good bacteria) that digest the ammonium and organic matter that may be entering the water.   The nutrient load in the water is reduced, so the density of any potential algal blooms is also reduced. Also because the water column is now well mixed,  the algae can not form a dense cover over the surface.   The biological diversity of the water starts to increase, zooplankton become established, and these organisms start to eat the bacteria and the algae. Larger zooplankton then move in to start eating the smaller zooplankton, and these animals in turn act as a food supply for fish and birds. The objective to developed an ecologically stable and divers population of bacteria, algae and other organisms in the water, when this is achieved you will have productive water, with no nasty smells, that looks clean and clear. The air diffusers therefore provide the oxygen to support the organisms, and water movement to prevent chemical and thermal stratification. However the simple act of moving the water also shif6ts the Zeta Potential of the water which increases the oxidation potential. For example you would never drink water from a static pool, you would also instinctively drink water from a fast flowing stream. In the same manner if you take two tanks of water, and simply move the water in one of the tanks, then the water quality will be greatly enhanced, there will be no scum on the surface and after a few days at 30 deg C, the bacteria levels will be millions of times lower in the tank with an aeration system. How is this achieved
There are three levels to lake aeration and water treatment stage 1.  Aeration,  for oxygenation, destratification and zeta potential control stage 2.  Bio-augmentation....by the use of natural bacteria stage 3. NoPhos.....used to eliminate the phosphate, only required if there is a serious algal bloom. If the lake or body of water in non biological ( purely aesthetic with no aquatic life), then you may use NoPhos to give clean clear water with zero to low algae and bacterial levels. ACO may also be added, and the water will self sterilise, especially when exposed to strong sun-light.

The  above table assumes a water depth of 2  to 4metres,  if there are deep water sections in the the lake, then the amount of aeration may be reduced because the amount of water moved by the air lift effect increases exponentially as the depth increases. By way of example, a 10 acre lake with an average depth of 2m has a deep water hole at 6m. This lake should only require around 40  cubm/hr of air, this equates with 4 diffusers type 6.2.10. Very large lakes or reservoirs only need a small amount of aeration to generate a huge mixing effect with a dramatic improvement of water quality.

If the lake or lagoon received a pollution load from organic mater, nitrogen and phosphates, then the system needs to be sized in relation to the quality of the water and COD ( chemical Oxidation Demand) of the water. One diffuser code 6.2.9/10 and 10 cubm/hr of air supplies 25 kg/day of COD treatment.  If you system has 1000 kg of COD loading then you need 40 diffusers and 400 cubm/hr of air.