In natural unpolluted water, phosphate is relatively scarce, with values between 0.001 - 0.01 mg/liter (ppm). Phosphate performs important functions in aquatic life :
For skeletal development of fish, especially young, vigorously growing fish.
Vital for plants metabolism, although aquatic plants only need small amount of phosphate for growth.
In aquarium, aquarium phosphate often increases 100x ,1000x or even more from natural level. It's a perfect condition for algae bloom. In addition, algae can store phosphate in considerable amounts and therefore can live for a very long time with lack of phosphate condition. That's why, phosphate is often not recognized as the cause of algae bloom.
How to prevent excessively aquarium phosphate ?
1. Fish Food.
As mentioned above, aquarium fish need phosphate through their food. Fish digestion should be considered when providing their diet. Young, vigorously growing fish secrete less phosphate than adult fish fed with the same type & amount of food. So, it's important to feed your pet fish with high quality food which meets the specific needs of the species and their growth-stages to minimize the aquarium phosphate pollution.
Frozen food, like bloodworms has a high phosphate content. You should defrost it first, then wash it using a strainer to remove the phosphate pollution.
It's also important not to overfeed your fish to avoid fish overwaste. Uneaten food also increases an aquarium phospate level significantly. So, feed your aquarium fish with care and observe their feeding habits.
3. Dense aquatic planting can keep aquarium phosphate at a low level.
4. Use only phosphate-free water for regular partial water change. You should check your tap water.
If your tap water contains high phosphate, you can use:
Phosphate Remover Media. It is a Chemical Filter media that usually contains ferric oxide, an iron-based phosphate binder ideal for use in aquarium filters, it will absorbs phosphate, silicate, and organic compounds without leaching adsorbed substances.
Liquid Phosphate Remover. It usually contains Lanthanum as the basic ingredient. Lanthanum has an affinity for phosphate molecules, basically binding with and forming Lanthanum Phosphate, it also has (although not as high) an affinity for Carbonates which in the absence of phosphate it will bind out of the water.
Therefore, you should check with a test kit whether there is any phosphate present and secondly add a little KH Buffer
before and after dosing so as to maintain your current KH levels.
The cloudy seen after dosing depends on the concentration of phosphates ie. slight haziness- low phos levels, milky appearance-high phos levels.
Lanthanum phosphate / Carbonate is easily removed by skimming or other forms of mechanical filtration like filter wool etc.
Aquarium Water Chemistry 
before and after dosing so as to maintain your current KH levels.
