- A complete site dedicated to Koi in the garden pond, Sections on Koi Health, Pond Construction, Pond Filtration, Photos of Ponds, KOI USA Magazine, Library of Koi & Pond Articles ...www.akca.org
- faq.thekrib.com/filters.html
- www.netpets.com/fish/reference/freshref/carbmeth.html
- www.aqualink.com/columns/k-hands3.html
- www.athiel.com/lib/ugfilterarticle.htm
