Oh man, you touched on something I love. You can make a
Benthic Zone (<- click on both _>)
Cryptic Refugium and another good link here (
Cryptic Zones), where sponge, tunicate, calcareous feather duster, etc. can grow along with some bugs. But you have to go looking for these organisms from a variety of other hobbyist tanks because only a few of these exist in the typical hobbyist system.
I set up a 3 tank system where water pumped from the no artificial light Benthic tank up to a very lively tidal pool tank located in a south facing window where there was a huge diversity of high light organisms, including algae. (I kind of patterned it after the west coastal regions where deep nutrient rich water wells up from the pacific towards the reefs.) Water then drained to a tank with lots of different fish including mildly predatory fish, then back down to the Benthic Zone tank. It was awesome. Later I exchanged the middle tank for a frag tank with a Carlson Surge Device(look it up

).
This was early in the age of digital photography so I don't have any pics, sorry.

Yes, it was a long time ago. I was inspired by a discussion with Steve Tyree at a seminar in Boise at
GARF.org and I even bought Steve's (at the time) newly published book on the topic.
Have fun with the project. Let us know how it goes by posting in the Tank Build section and feel free to contact me with any questions.
Aloha,
Mark
808-345-1049
P.S. Remember though that the kinds of bugs that many of our fish eat come from zones where algae grows thick. Lot's of those bugs are herbivores so they cannot do so well in a cryptic environment
Edited by Mark Peterson - December 22 2016 at 4:36pm