OK everyone, its the 2minute warning 4th qtr down 7pts on the 1yard line, it's 3rd & goal.
in this scenario I "believe" that every any pro football team will score a TD the majority of the time.
so goes with bio media. majority of the time it is useful - "required or needed" ? well that Q? can be answered I'm sure by others who have experience w/o bio-media fancy smancy ceramic rings.
in fact, I will add my experience of the good ole days of days gone by - I remember buying a set up & the filter came with only filter floss & carbon. back then that was all that was needed for filtration to get up & running. how about those corner in the tank filter boxes that work fine with guppy goldfish tetra etc. small tanks? no bio-media special rings needed there.
in fact, back then in my 10 gal tank (which today I will admit was overstocked) I have to presume that all the natual processes were working fine since all I had was a cheapo part of package deal HOB filter with filter floss (that got dirty plenty fast) & carbon (which was used religiously). later on did the same with a 15gal & then a 20gal. this mind you was back in the 70's! didn't know about bio-media or if I did wouldn't have been inclined to buy em.
so to continue - I would get lazy & not change the filtger floss for days on end, like months. fish did fine. actually none died for quite a long time. even when I added more fish (& no QT accept acclimating the bagged fish) the worst that happened was I got Ich.
& never did frequent w/c's. when I did a w/c, I would stir up the gravel with a very thin long tube (I think it was a suction tube) which then I proceeded to ("siphon out the water" - actually scooped cups of water out) so I could refill (& get this! with aged water! not conditioned by Prime or any other product!).
so in my long ago naive lack of knowledge lazy days of fishkeeping, I did just fine w/o the special bio-media rings/spheres/jagged glass, etc. cuz guess wHere it all was? on the glass, on the filter tube, the heater/thermometer, decoration & in the filter itself (what with the thick filter floss having a nice layer of slime).
so for both sides of this debate - use of ceramic rings can't possibly hurt the OP, so any size would be fine to use. if the OP chose not to use, well I don't think (uh oh, opinion coming! no scientific foundation to base it on - except my limited experience & science project) - I don't think it is really needed.
there I said it & you can't make me take it back! no backzies!!