The claim for anoxic filtration is that it attracts and converts ammonia and nitrate and converts it to harmless nitrogen very effectively. In this way it serves as an extremely effective fertilizing machine for water plants that may be planted in the filter media.

Quote from a internet site:

One of the group members responded that anaerobic bacteria were also necessary.  I had never heard a good word spoken about anaerobic bacteria in a koi pond before and requested some more info.

This led to several exchanges until someone posted a link to information on anoxic filters, http://www.mankysanke.co.uk/html/anoxic_filtration.html. Can’t give proper credit since this entire discussion seems to have disappeared from Linkedin for some reason, but I found the information on anoxic filtration very interesting.

So much so that I plan to incorporate anoxic filters in my new pond design.  The principles can also be applied to any plants you may have in your pond.  That’s what I did this year when repotting my water lilies and lotus.

I drilled the pots full of holes to allow free passage of water.  I then lined the pots with porous weed barrier and replaced the native clay with Special Kitty natural clay kitty litter from Walmart.  I added a cup of First Layer Pure Laterite in the center of the pot and covered everything with a thick layer of stones.

The claim for anoxic filtration is that it attracts and converts ammonia and nitrate and converts it to harmless nitrogen very effectively.  In this way it serves as an extremely effective fertilizing machine for water plants that may be planted in the filter media.

The details are quite complex, but fascinating.  For more information check out the link I provided above.  To see a slideshow demonstrating how I built my anoxic filter/flower pots go here: Anoxic Filter Flower Pots