Howdy,
Ceramic rings are bio-mechanical filtration media and do a good job by themselves. I used to run a heavily stocked 20 gal with ceramic rings only - as every canister guy did about 20 years ago. It went fine, I never lost a fish. I think the sintered glass came out not quite 10 years ago, at least in Europe.
Sintered glass filtration has the advantage to provide more bacteria in your existing system, reducing the likelihood of ammonia/nitrite peaks and being more forgiving when you clean your filter: Even when you wash it out thoroughly, it still harbors enough bacteria to get going right away. Furthermore, it allows "over"stocking to a higher degree.
IMO, sintered glass is like ABS in a car: If you are a foreseeing and good driver, you hardly ever need it. But when you need it, it's good to have. Cars run without ABS, and fishkeeping was quite possible before the dawn of sintered glass.
I do not have numbers for EhfiMech, but Substrat and Substrat Pro have about 20.000 sqft/gal surface area. Bioballs have about 20-30 sqft/gal. Cellpore says their product has the surface area of 1 cubic inch = 300 bioballs, which makes it almost 50.000 sqft/gal for their product. It sounds like a lot, but it is not as big of a jump as the introduction of sintered glass was (orders of magnitude). After all, it only has about twice as much surface area. In biological systems, twice as much is not that significant.
Furthermore, surface are alone does not determine filtration efficiency. Judging from their website, water runs right thru the block of Cellpore. In contrast, other structures (round, hollow, rings) create larger turbulences, which create an even distribution of flow thru your media across the entire filter and cause more small dirt particles to settle down.
My advice: Stock your (canister) filter with about 1/3 ceramic rings and 2/3 sintered glass media. It works for me.
Harley
