This is from the first grow I did, PF tek style but with a few updates. I did a couple monotub grows a year later that went great but I can't for the life of me find any pics.
The white pebbles are perlite and the cake is mostly rice bran meal and fine vermiculite, with a little coffee and gypsum.
It's something to read about. I don't have personal experience with combining them, but I think it depends on dosage and your specific physiology.