How to Convert From Foam to Bio Balls in My Pond Filter

Written by melanie l. marten
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How to Convert From Foam to Bio Balls in My Pond Filter
Convert from foam to bio balls for clear pond water. (koi pond image by MPH from

Converting from foam to bio balls in your pond filter is an easy process that can improve biological filtration of pond water. Take care to maintain the viability of the beneficial bacteria colonies existing in the filter foam. Make the conversion gradually so the health of the pond is not compromised.

Skill level:

Things you need

  • Bio balls
  • Bucket
  • Garden hose
  • Chlorine eliminator solution
  • Existing pond filter with foam
  • Utility knife
  • Net bag

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  1. 1

    Pour enough bio balls to fill your pond filter box into a clean bucket. Run a garden hose over them until they are completely free of dust and debris. Fill the bucket with water and add dechlorinating solution. Follow the directions on the bottle for the amount needed per gallon. This will remove chlorine residue from the bio balls so it does not kill off any beneficial bacteria in the filter.

  2. 2

    Remove the old filter box from the pond, and remove all the foam pond filter media. Use a utility knife to cut off any attached foam or batting. Put a quantity of this foam into a net bag, such as those that hold onions at the grocery store. Tie the top so the foam cannot float out. Do not rinse this filter foam.

  3. 3

    Pour the cleaned bio balls into the filter box until it is full. Lay the net bag with the filter foam inside it on top of the bio balls in the filter. Using the old filter media in the new filter for a week or more will allow the beneficial bacteria to colonise on the bio balls.

  4. 4

    Replace the filter box lid and all hoses and tubes connecting it to the pond pump, waterfalls or fountains. Fill it up with water taken directly from the pond -- not water from the garden hose -- and turn it on.

  5. 5

    Wait one or two weeks before removing the old filter foam from the filter. The bio balls should begin to have a coating of green or brown and some slimy material. Do not wash this off or dislodge it when removing the old filter media. It is the beginning of beneficial bacteria colonies essential for maintaining healthy water. Replace the lid and allow the filter to continue running as usual.

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