How high should the phosphate content in the aquarium water be?
In an aquarium with many plants, a phosphate content of 0.1 to 0.2 mg per liter of water is optimal for plant growth. Phosphate is consumed by plants as a nutrient. Excess phosphate that is not absorbed by the plants is used by algae. Although it is possible to operate algae-free aquariums even with higher phosphate levels, the risk of too many algae growing increases with the level of phosphate levels. According to American sources, tests have shown that 30 mg phosphate per liter of water leads to algae growth.
How phosphate gets into the aquarium water
When the water is hard, waterworks often add phosphate to the water. Phosphate prevents the water pipes from calcifying. Otherwise, it comes mainly from the fish food via the metabolism of fish and bacteria into the water.
- Tap water contains phosphate.
- Dry and frozen food contain phosphate.
- Means that lower the pH value contain phosphate, e.g. B. Peat and oak extract.
- Some plant fertilizers contain phosphate.
- Plants can store phosphate. When plant leaves decompose, the phosphate is released.
- Algae can store phosphate for a long time.
- Phosphate accumulates in the substrate and is constantly being dissolved back into the water.
How to remove phosphate from the aquarium
If the tap water is already contaminated with phosphate, it can make sense to use an osmosis system or an ion exchanger. This is particularly useful when soft water is required. Otherwise other options are cheaper. Phosphate is removed from the aquarium water by changing the water and the uptake of phosphate by plants. With economical feeding and a sufficient number of fast-growing plants, no excess phosphate accumulates.
But there are also phosphate-binding agents that can be packed into the filter. “JBL PhosEX ultra” is the most effective. .
Many brands offer this type of filter material. With all brands, however, you have to reckon with a slightly increased pH and KH value, which you can compensate for with the next normal water change.
- Large and frequent water changes can quickly remove phosphate from the aquarium if there is not already too much phosphate in the changing water.
- If the cause is too much feeding, the entry of phosphate is reduced if less is fed.
- Fast-growing plants consume phosphate.
- Remove dying plant leaves.
- Some indoor plants remove phosphate from the water through their roots, e.g. B. the ivy.
- Commercially available chemical agents bind phosphate.
- Zeolite binds phosphate.
- Osmosis systems or ion exchangers remove phosphate from tap water.
Remove phosphate with steel wool
In principle, the phosphate content can be reduced with steel wool. The phosphate precipitates as iron phosphate. However, since steel wool usually contains additives that are not wanted in the aquarium, the use of steel wool is not recommended. The same applies to the use of nails, which today are no longer made of pure iron but contain numerous additives.