I wasnít trying to be rude, sorry if it came off that way.
What I was trying to point out is that a Inca snail is a oxygen breathing creature and as far as I know they only inhabit the aerobic areas of the gravel. If you know of some documented study that contradicts that Iíd love to see it. One thing all living creatures have in common is intense desire to stay living.
The other part about specific media and building denitrification filters goes back decades, I was building them in late 90ís-2000ís. As @Edward
alluded to in his post you can set up a better nitro filter in your canister. Why itís better is because you can prefilter water hitting it and it stays stable, none of gunk gets in there and clogs your denitrifying media.
Many designs for these types of filters can be found on internet. The specialized media like FilterPro BioHome, Seachem, Brightwell aquatics have been around for decades.
Basic designs would be like couple 3Ē acrylic tubes hooked together with a a pvc U at bottom. Input youíd T off a canister or sump with .25-375Ē feed line w/ a valve. Input would be a filter with bonded filter pad followed by 5 micron felt. Rig up hooks so just hangs on edge of sump or tank. After about 2 wks letting it seed start taking sample and testing water, water on exit side still has some nitrate you slow flow down a bit so aerobic bacteria a start has more dwell time and depletes more oxygen and more of media goes anaerobic. Youíll find that once itís seasoned and functioning properly you have can dial it in to what ever nitrate level you want simply by controlling the flow. Add a crapload more fish you can add a extra U shaped filter to handle it.
Canisters, if say you have Rena or other 6Ēish filters, Iíll take a 4Ē tupperware tub, cut 3/8Ē hole bottom edge, opposite edge top cut a 3/4Ē hole, glue some fiberglass window screen to cover holes. Then get 1.5-2Ē lava rock and some .25-.5 lava rock. Arrange as many big chunks of lava as you can then fill about .5 to .75 of container with smaller grade lava.
That container, 60% of water flow in canister will bypass it, micro-current that flows through it, give it about 3 months and it will settle in. For about $6 you can have a nice little nitro filter for a 30gal.
Denitrifying is easy if you move it out of main tanks gravel bed, maintain a mostly aerobic gravel bed, let the tank/plants do best they can and then only if need (usually excessive fish load) set up de-nite stage after tank filter.
Again Iím sorry if I came off as rude, not my intent. I started keeping aquariums almost 40 years ago, one of my best friends is a aquaculturist/biologist. The in tank flux of owner is one variable you canít control, the processes governed by nature you can predict.