That is a good decondary impact.
To increase the contact area to denitrify
I went to a bee home congress and they were very insistent on how each species have very specific needs in term of 'house sizes'. I'm trying to apply that into my tank.
Whats is sold is regular in size.
Nothing as good as granular rocks made via several kind of animals.
larger rocks dont have as much surface area as those smaller ones , and sand is simply not big enough to stay clean.
I had a healthy red tree sponge until I removed most of smaller sized rocks becose my pistol shrimp felt too safe and started to harass my fishs.
Ill deal with the shrimp later.