The chicken grit I use is like that of size 1 chicken grit as shown on Rick's photo, that's the size we get from the chicken grit bags we get at our local Ace hardware. I use it to top dress my succulent containers. Before I use either perlite, pumice, crushed lava rock, kanuma or akadama. I also mix in some of this to my tropical indoor plant's soil, it helps to give air at the root zone. Though knowing what type of plant you are growing indoors is important, the more tropical ones will appreciate some more moisture retention in its media than the succulents. And some succulents do go partially dormant during cold season, so they need really fast draining soil and proper watering intervals.
I have used coco coir with my epiphyllums, and some orchids, they are okay with it. Some orchids are more water needy like the Oncidiums and coco coir is really good for them since it holds water longer. My Phals, I use chunky bark mixed with clay rocks and have experimented with baggies of clay rocks. I forgot the name of this material I used as baggies, but it is really nice, lots of holes, porous enough to allow quick air flow but at the same time holds some moisture which the Phal roots needs.
So pretty much the best soil mix for indoor plants will depend on what type of plant you are going to grow. Different type of plants, different types of media.
