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General pond & water

What is the maximum amount of fish I can have in my pond?

For every square metre of pond surface area, you can have 60cm length of adult fish (don’t include the tail in this measurement). See our fish article for more information.

How do I work out the volume of my pond?

The average length x average depth x average width in metres, multiplied by 1000 will give the volume in litres.

The average length x average depth x average width in feet, multiplied by 6.23 will give the volume in gallons.

Alternatively please use the Dosage Calculator page to help.

Why do I have foam on my pond?

Pond foam is caused by surfactants which are attracted to the surface of air bubbles and strengthen the bubble so it does not pop, but creates an unsightly foam.  These surfactants may be artificial chemicals such as detergents.  However, the most common cause of pond foam is high levels of protein, from the partial breakdown of organic matter, building up in the pond.
There are a number of products available which are effectively wetting agents, which affect the surface energy of the bubbles, causing them to pop, and therefore break up the foam.  However, it is also necessary to find the cause and eliminate that also.  We also recommend the following:

  • Carrying out water changes to dilute the surfactants.
  • Removing excess sludge from the bottom of the pond.
  • Checking that the fish stocking level is not excessive; maximun of 60cm of adult fish (i.e. 6 x 10cm fish) to every square metre of surface area.
  • Adding Sludge Buster to remove dead organic matter.
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