Phosphates, Green Water and Algae
Phosphates are one of the primary contributors to the growth of algae in an aquarium, both as algae blooms causing green water, and as algae growing on the glass and ornaments.
High levels of phosphates may also lead to newly introduced fish suffering from shock, resulting in disease and death.
Where do Phospahates come from?
Phosphates are introduced into an aquarium in many ways, tap water being a major contributor. Other sources of phosphate include pH buffers, carbon, salt, fish food and overfeeding,
Tap water can contain very high levels of phosphates. These are harmless to humans but will act as a fertiliser in an aquarium.
Phosphates can also be generated within an aquarium through a heavy fish load, wasted fish food, and also algae or plants which have died.
If phosphates are a problem the source must be found.
A phosphate test of your tap water is the first step. This will determine whether the source is tap water or from your aquarium.
If tap water is the source of the problem then the phosphates should be removed before the tap water is used in the aquarium. This can be achieved by using Reverse Osmosis water (using an RO unit), bottled water, or tap water which has been passed through a phosphate removing resin (eg. Rowaphos).
If the phosphates are orginating in you aquarium you need to find the source.
A few things to look for in your aquarium:
Over feeding, cut down on your feeding and monitor your phosphate levels.
Stir your gravel or sand and see if any detrtus is disturbed. Your gravel bed may require a vacuum.
Check your filter for detritus. External filters can hold large amounts of muck at the bottom of the cannister and this can add to a phosphate build up.