The total phosphorus entering water bodies per year in Germany is approx. 23,000 t (data from 2005, source: Federal Environmental Agency). Broken down to a single square metre of water surface, this corresponds to 2683 mg / m² of phosphorus, which corresponds to 8229 mg of phosphate per m². In a pond with a depth of 2m and a rectangular shape, this would result in phosphate pollution amounting to 4.1 mg/l per year. The sources of phosphorus pollution are the following according to the Federal Environmental Agency (in descending order): Point sources (e.g. controlled fertilization), urban areas (carried in dust particles), groundwater, erosion, surface water, entry through the atmosphere and drainage. Even if all of the sources do not apply to garden ponds and even if not all phosphates are available to algae, it is a fact that phosphorus (phosphate) from the surroundings is constantly entering our garden pond water.
hosphates are the primary nutrients for algae growth in a garden pond. Phosphate levels of 0.35 mg/l (lower limit of the definition of eutrophic = nutrient-rich bodies of water) already suffice to trigger significant algae growth. Many algae species are able to store enormous amounts of phosphates in their cells (e.g. Volvox algae can store 140,000 times the water concentration and Nitzschia algae can store up to 3,800,000 times the concentration which can be measured in the water). As a result, tiny amounts of phosphates are enough for these algae to grow permanently. The storage capacity also explains the phenomenon of algae growing in a pond without any measurable phosphate. As a consequence: If there are algae present, then phosphates are also present, regardless of whether they can be measured in the water or whether they are bound in the biomass of plants, algae and animals or are in the sediment.
Under these circumstances, it is very clear that the permanent export of phosphates out of the medium, namely the pond water, is the only way to keep algae levels low in a garden pond in the long term. The most effective way to do this is to use JBL PhosEx Pond Filter . By regularly replacing the granules, phosphate is removed from the pond permanently, i.e. exported. The use of phosphate binders which are added to the pond water only provides a short-term means for rapidly decreasing the phosphate level. Export is the only viable long-term solution. In nature, nutrients are also exported from the pond in the form of animals which develop as forms of larvae in the water and then change over to a terrestrial life (e.g. amphibians) and aerial life (e.g. insects). Figuratively speaking, every small common toad which has completed metamorphosis from a tadpole to a toad and then migrated carries two small bucketfuls of phosphate on land. Nevertheless, the overall balance of nutrients entering the bodies of water always remains positive with the following result: The pond fills in!
Every natural lake with no outlet will fill in in the course of time. This may take centuries to several thousand years, depending on the size, volume of water and pollution. The process cannot be avoided because nutrients from the surroundings are constantly entering the water. However, we don’t want our garden pond to fill in, so that it is advisable to regularly use JBL SediEx Pond . The bacteria contained in this two-component system effectively contribute to reducing pond sludge.