There are two main algae growth forms. String algae, or hair algae, is one of these main forms. The second form is free floating algae, which are very small and can give the appearance of being a solid mass but will easily separate when the water surface is disturbed. String algae develops on the surface of the water in a matting form. Like all algae, string algae requires light, water and nutrients to grow. A bloom of string algae signals an overabundance of nutrients in the water that are not being consumed and broken down by fish, plants and bacteria.
Commercial fertilizers can find their way into the body of water by runoff or by other means of introduction into the pond such as fertilizer tablets used in water plants. The excess nitrogen, phosphorous and other trace minerals found in commercial fertilizers are the principal culprits in creating the overabundance of nutrients that feed string algae and quickly multiply it. Correct the imbalance of nutrients by reducing or stopping the use of topical chemical fertilizers in the acreage surrounding the body of water affected by the string algae.
Internal Systemic Imbalance
When too many nutrients such as nitrogen build up, it can also be due to too much fish waste that is not being broken down or not enough plant material which leads to an internal systemic imbalance within the body of water. This can be corrected by upping the bacteria counts or planting more aquatic plants and rocky surfaces. Water plants such as lilies can be removed from their soil pots and planted directly between rocks in the pond to boost their consumption of nutrients and help to naturally control the string algae. Rocks built up in the water will provide a place for bacteria to colonize as well.
Chemical Controls for Algae
When string algae colonizes a body of water and natural control measures fail to get it in check, chemical treatments can be employed. If you have plants, animals or fish living in or relying on the water, use only animal- and plant-safe algae treatments such as AlgaeFix. If you have algae in a fountain or decorative pool with no plants or animal life, chlorine and other algae-checking chemical formulations can be mixed into the water to keep the algae at bay.