Pond algae behave like other pond plants

Because pond algae are plants they thrive on sunlight and nutrients (fertilizers) and warm temperatures. This is why pond algae problems are really worse in summer

Aquatic Plants and Algae ... If a pond has aquatic plants in it then these plants will compete with algae for the available nutrients. In this way algae problems can be reduced but possibly not eliminated. For this reason if no other it is a good reason to introduce a range of aquatic plants into a pond or the circulating water system.

Fish eat plants so to protect their plants many pond keepers plant waterfall areas or even create a separate pond just to hold plants.

In ponds that contain only plants the problem of algae is normally much reduced for the reasons that nutrients from fish food are taken up to some extent by the plants..

In fishponds it makes sense to always underfeed fish to reduce algae problems. Fish can live quite easily on what is naturally available in most ponds so long as the pond is not over-populated.

Suspended Algae are tiny (about 4 microns, so small they pass through any bio filter)

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.

Green/brown cloudy water is normally caused by millions of algae remaining suspended in the water. Each algae is about 4 microns in diameter (1 micron is 1 millionth of a metre or extremely small).

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 re-circulated. By the way most filters suffer from this design problem so do not think it is a problem with yours. It is almost impossible to design to remove algae by filtration alone.

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, 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. Equally they are fertilisers for algae - remember algae are plants.

If there was no nitrate and phosphate there could be no algae.

Even if there are no fish in the pond it is possible to get algae problems. This is a common problem these days even in large waterways and is the result on nitrate contamination of groundwater from the widespread use of fertilisers in fields.

All tap water contains nitrates and in some areas probably phosphates. Also wind blows debris into ponds and water features and this debris also contains these substances.

For guaranteed crystal clear clean and healthy pond water buy low cost combo biofilters and UV units containing the best biomedia, Alfagrog, by clicking this link Combo filter & UV

"The Complete Pond Solver" by Tony Roocroft

2005 Edition. Essential reading for anybody who wants or has a garden pond. Get 12 Excel pond calculators free as well as "Water Lilies and Pond Aquatics" ebook also free

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