Please show a picture of your filter. I use the Fluval Pre-filter ceramic six sided pieces
and they are not smoth. Not a very coarse feel either.
One should have a prefilter before them that keeps the detrius/mulm etc off the
bio-media. The bio-media works best when you never touch it ergo the filter before the filter to keep the bio-media clean. This is a picture of one of my filters just after setting it up. I keep extremely low bio loads so dirt on the media doesn't hurt as the bottom is still clean. So there is no pad/sponge/screen etc for a prefilter in mine.
This shows both the Fluval ceramic that I use and the Bio Bale bio-media from the bay
which I tried and found to work well. It is intended for a canister filter.
Guess I should add that the water comes in on the bottom left and goes down through the bio Bale first.
Then another very good bio-media is Matrix and that one is not very expensive.
In my other tank I also built in the filter and use the Bio Bale on top of Matrix in that one.
I will say this about the whole issue. I had lots of RCS in that tank pictured. The colony grew in there so the bio-media had plenty of time to adapt.
One day there was some java moss pieces in the top of the bio Bale which had gotten in over a period of time and lots of small pieces of trimmings. So I took out about 25% off the top and rinsed it well and took out the trash from it. But then someone called me and I had to go for a while so I forgot to replace the media which I took out.
The next morning most of my RCS were dead on the bottom of the tank.
Mostly saying that IF you have a heavy bio-load and especially if it's over 100% according to the Aqadvisor...any bio-media will do this if tampered/w as the filter is
using all available space for bio bacteria.