The benefit of aerators and fountains
Lakes and ponds receive oxygen by natural processes like surface disruption through wind and rain, and aquatic vegetation converting CO2 and light energy into oxygen. These natural processes are not always a reliable source of oxygen, which puts your lake at the mercy of the weather. In Texas, that can be good or bad, depending on the kind of year we are having. Aeration provides your lake with an insurance policy by delivering a constant and predictable source of oxygen. This policy provides you with overall better water quality, algae control, better growth rates in fish, and better fish health and immunity. The most important factor to adding aeration is the reduced risk of losing all of your hard work to a fish kill. Nothing is quite as aggravating as coming home to a lake that stinks of dead fish, especially when adding a little aeration could have prevented the whole thing.
Decomposing organic material (leaves, fish waste, etc.) settles to the bottom of the pond and begins to decay. As it decays it depletes oxygen and releases toxic gasses (nitrogen, ammonia, etc.). Without proper aeration, these toxic gasses become trapped in the deeper, colder, and now oxygen starved water. The lack of dissolved oxygen in the water, known as an anaerobic condition, blocks out beneficial bacteria that act to break down the decaying material, thus adding to the problem. This natural process called stratification occurs in all bodies of water. Stratification does not pose an immediate issue. The issue occurs when the layers suddenly mix (a turnover event) due to surface cooling by wind, rain or fall weather. Often times the surface layer does not contain enough oxygen to compensate for the lack of oxygen in the bottom layer. This causes an overall lack of oxygen and ultimately a fish kill.
The result of an unbalanced ecosystem mixing of nutrients can lead to a build up of algae. Algae consume nitrogen, ammonia, and soluble phosphates and release oxygen through photosynthesis. The problem occurs when blooms of planktonic algae race out of control, thus producing high amounts of oxygen during the day and using most all of it up at night. The result is typically a total fish kill. Having an aeration system levels out the natural cycle and maintains an acceptable level of oxygen in the water year round.
How to choose between aerators and fountains
There’s no doubt about, oxygen is good, whether you breathe through your nose, your mouth or a set of gills. Luckily, choosing which apparatus you are going to use to put more oxygen in your pond isn’t very complicated.
If you want an aesthetic component to your pond aeration and you don't plan on moving it around, a fountain would be a good choice.
If you want to be able to move your aeration device from one pond or lake to another, you should choose an aerator.