How Does Light Affect Pond Bacteria?

Natural Light

• While natural light does contain the UV rays necessary to alter the bacteria cells enough to destroy them, the concentration is not enough to be consistently effective. For instance, if a portion of your pond is shaded by trees or bushes, that area of the pond will be more susceptible to bad bacteria growth. However, even areas that are in full sun can develop a bacteria problem. Therefore, relying solely on the natural light may still result in problems.

UV Water Sterilizers

• UV water sterilizers emit concentrated UV rays into the water, which is more effective than the UV rays from natural light. The water from the pond flows past the UV sterilizer. Any bacteria that is present in the water that flows past the sterilizer is damaged and therefore, eliminated. However, any bacteria that has attached itself to a surface in the pond and is not free floating will not be eliminated with this method.

Balance

• Because light has little effect on the bacteria and algae that cling to the walls of the pond, it allows for a good balance of bacteria within the pond. Not all types of bacteria are bad for a pond. In fact, some types of bacteria are necessary to the overall health of the pond and its fish. Bacteria that is bad for the fish float freely in the water and reduce the amount of light the good bacteria receives. When the good bacteria does not receive enough light, it dies, disturbing the sensitive balance in the pond.

Bacteria Growth

• In addition to killing off the bad types of bacteria that float among the water, the algae and bacteria that grow on the walls of the pond need sunlight to survive. Especially when the pond is shallow or new, the bad bacteria can quickly overtake the pond, blocking the sunlight access to the good bacteria. The makeup of the bad bacteria is not receptive to UV rays. Thus a UV-light sterilizer helps wipe out the bad bacteria, encouraging the good bacteria to grow and thrive.