Do you have the usual problem of green water, which does not go clear and even after changing the pond water?

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Concepts:

algae, pond, water, filter, fish, nitrates, microns, food, plants, fertilisers, phosphates, common, design, surfaces, bigger.

Summary:

- Like most of us the more food, the more oxygen and the more sunlight the better and bigger the algae grow.

- Not all algae are green and not all algae are minute in size and nor do they all remain suspended in water giving that pea-soup appearance.

- First of all the usual problem of green water (sometimes brown) which does not go clear and even after changing the water the algae re-appears very quickly and this happens even if you have a filter installed.

- The reason why algae is not removed in many filters is due to its small size - if the medium in your filter has gaps/pores greater than 4 microns in size then the algae will just get recirculated.

- By the way most filters suffer from this design problem so do not think it is a problem with yours.

- Algae growth is most common in ponds where conditions are most suited to their requirements - lots of fish being fed lots of food, warm water as it is in summer here, and strong sunlight.

- The waste products from fish eventually create nitrates in the water and most pond food contains phosphates and lots of nitrogen.

- These are fertilisers for plants as you know from general gardening.

- Algae that grow to about 1 cm in length and are seen on pump surfaces, rocks, pump filter sponges and the sides of ponds are normal.

- Do not try to remove them by sweeping the pond walls for example because they will keep coming back and if left alone reach an equilibrium point.