Pumping the Algae Out of Your Pond
One statement to remember with ponds is, Before it's green you have to clean. There are two ways to keep your water pristine and keep a limit on algae (microscopic phytoplankton). The first is to buy a large pump (and there is never anything wrong with buying a larger pump than you need) and the other is to keep it clean. Advice? Buy the largest and best pump you can afford. It will take less cleaning, resulting in less of your time, and it will create a better living environment for fish and pond plants.
In order to maintain proper flow, circulation and aeration of your pond water, and to keep clean water moving into the pond, you will definitely require a good pump. There are four ways to filter your pond: mechanically, biologically, chemically and using UV sterilization. Mechanical filtration removes particles from the water, it does not remove algae. Biological filtration allows algae to grow on the surface area and the biological filter (like fish excrement) breaks it down. The addition of chemicals may kill unwanted algae. However, most ponders try to avoid this route due to environmental concerns. UV clarifiers not only kill algae, but it also kills pathogens that could give infections to fish.
Essentially, there are two different pump options you can choose from: a waterfall (aquafall) or a submersible pump. Your choice will likely depend on whether you prefer the soothing sound and look of a waterfall and your budget.
When shopping for a pump, you will need to get the right size for your pond. Pumps are measured according to their pumping capacity, either in gallons per hour (GPH) or gallons per minute (GPM). Your pump should be able to pump at least half of the pond's water volume per hour.
If you happen to have a very high waterfall, it might be wise to have separate pumps for the waterfall and filter. This is because you will require more power for the waterfall, but the same pump might be too powerful for the filter.
If you have an extremely large pond, a gas-powered pump would be the most practical. For the best energy efficiency, a magnetic drive pump would be the most practical.
Pond pumps are usually priced between $70 and $380, depending on the size and power your pond requires.