Copper Sulphate Swimming Pools

The Copper Sulphate for swimming pools, CuSO4, is used as a algaecide in the preparation of swimming pools during the summer season. An algaecide is a chemical used to destroy algae (single or multicellular chlorophyllous microscopic plants). They reproduce by division or sporulation and encourage the growth of micro-organisms such as bacteria and fungi.

Virtually all swimming pools require the use of an algaecide. The copper sulphate is one of the most widely used.


In these 2 images you can see different pools. In the first image we show you 2 pools with greenish water due to algae and organic matter. The lower image shows you a pool that we are used to swimming in. The colour is often the best indicator of the state of the pool. 

Swimming pool with algae Swimming pool clear water

The green colour is due to algae, which are unicellular micro-organisms of plant origin, with a great capacity to reproduce under certain conditions.

To repair the pool when this happens, it is recommended to use a biocide such as Copper Sulphate which will act as an algaecide. Copper sulphate for swimming pools is the common copper sulphate (pentahydrate), which you will usually find commercially.


The dose to be used will depend on the amount of organic matter in the water. It also depends on whether it is a shock treatment or if it is applied as a preventive treatment for the winter. 

For a summer preparation cleaning of the water, a reference dose would be 5-10 grams per m3 of water.  1 m3 equals 1000 litres, so for a swimming pool of 100 m3 would need 0.5-1Kg of copper sulphate approximately. We can take these quantities as a reference.

1m3 of Water - (1.000L Water) - 5-10 grams of Copper Sulphate
10m3 of Water - (10.000L Water) - 50-100 grams of Copper Sulphate
50m3 of Water - (50.000L Water)- 250-500 grams of Copper Sulphate
100m3 Water - (100.000L Water) - 500-1000 grams (1Kg) Copper Sulphate
2500m3 of Water - 12-25 Kg of Copper Sulphate

Dissolve the product beforehand in a small amount of water and spread over the entire surface of the pool.


  • Make a calculation of the volume of water in your pool (if you don't have it in the manufacturing plan). With this volume, estimate the quantity of copper sulphate.
  • Dissolve the copper sulphate in a small amount of water first. Once dissolved in the small amount of water, pour the solution into the pool.
  • Circulate the water for 1-2 hours. By circulating the water you will be dissolving all the copper sulphate in the pool. Leave overnight (8-10h) for the copper sulphate to act on the micro-organisms. Copper sulphate is a biocide that will act on the suspended micro-organisms. Subsequently, we will need a product that will precipitate them. 
  • Once it has settled overnight, or at least 8-10 hours, a flocculant is needed to precipitate the suspended particles. One of the most commonly used flocculants is Aluminium sulphate. Aluminium sulphate acts as a flocculant, binding the particles and precipitating them to the bottom of the pool.
  • Leave the aluminium sulphate to stand and act for at least 1-2 hours.
  • Clean the impurities left on the bottom and walls with a hoover.
  • Recirculate the pool water.
  • Measure the pH of the water and its residual chlorine, check that all values are within the established parameters. 
  • To prevent the formation of micro-organisms, the use of a pool protector is recommended. 

In case the use of copper sulphate is preventive (the pool is not green, but copper sulphate is poured in when filling the pool as a preventive measure), use only as a preventive measure. 2 to 4 grams per m3 . If it is for winter maintenance (ALL YEAR ROUND), then use 50 grams per m3 of water. 

OBSERVATIONS After applying the algaecide or copper sulphate, bluish-grey stains may appear, covering an appreciable surface of the walls and bottoms. They are due to the dead protein residues of the invading micro-organisms, and disappear on their own within 1 to 4 days.

Another use of copper sulphate is in agriculture, here you can see more: copper sulphate fungicideand is also an important component in the animal feed.


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12 thoughts on “Sulfato de Cobre Piscinas”

    1. Hello Rosina,
      It is very important to follow the steps for the application of copper sulphate in order to be able to bathe safely afterwards.

  1. Luis Eduardo Garrido

    Good afternoon my friend my pool has approximately 37 thousand litres of water how much copper sulphate can I put in it?

  2. Hola, aplique 500 gr de sulfato de cobre, está transparente pero muy verde, ahora está azul pero turbia, que debo hacer ? GRACIAS

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