Excellent feedback. I'm impressed. The floor buffing pad is a good idea but all of them I could find online have a hole in the middle, and I need a 20" dia disc of it with a hole offset.

This site is encouraging but they need a large minimum order:

111 Bio Filter Media Japanese Bio Filter Mat, View Bio filter mat, LANLING Product Details from Guangzhou Lanling Aquaculture Equipment Co., Ltd. on Alibaba.com

Found this on Amazon, while doing a search for the product just above:

Amazon.com: Puro-KleenTM Fish Safe Pond, Water Garden & Aquarium Filter Media- 24"x72" Mat 1.5" thick: Patio, Lawn & Garden

The 'Bio-mat' series of syllables seems to be key.

Wow. Check this cornucopia of images out:

https://www.google.com/search?sourceid=navclient&ie=UTF-8&aq=&oq=&rlz=1T4GGHP_enUS505US505&q=Bio+Filter+Media+Japanese+Bio+Filter+Mat&tbm=isch

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1986 300SDL, 362K
1984 300D, 138K