Pond Sludge Treatment
Sludge occurs in slow moving and static water at the bottom of ponds and lakes. It basically consists or organic waste from fish excreta and dead plants that drop to the bottom and becomes a thick brown sediment. The nutrients in it can promote the growth of unwelcome and harmful bacteria which in turn can reduce water quality affecting both flora and fauna. It can also make the water look cloudy and unpleasant. At worst it can produce noxious gases such as H2S (Hydrogen Sulphide) which give the smell of rotten eggs. All in all it is a bad thing to have and a good thing to get rid of.
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Blanket Weed is a long thin filamentous alga, which like Ulothrix thrives in ornamental ponds. As can be seen from the microscopic observation, the cells of Spirogyra are characterised by helical shaped chloroplasts which give the weed the pronounced green commonly associated with Blanket Weed. Its growth is increased by bright sunlight and shallow fast running water so that it will be found in water-falls and unshaded pond areas. In ornamental ponds which tend be stocked with fish, the tendency to overfeed causes additional fish excrement which contains nutrients favoured by Blanket Weed particularly nitrates and dissolved ammonia. This means that apart from normal growth by photosynthesis the weed will grow even faster.
The spores of Spirogyra can be preserved in the dry state for many years and come back to life when put into water. Ponds can be free of Blanket Weed for years and suddenly become infested. Pulling weed out actually releases spores produced by conjugation (see photo – bottom left), which then produce even more weed.
The proliferation of Blanket Weed is due to the fact that it grows very quickly in sunlight and if left unchecked can cause serious oxygen depletion in ponds. Additionally it can also cause stress to larger fish that find it an obstruction.
