Yep, you are right. Heres the bases http://www.amazon.com/gp/product/B01B68LYDQ/ref=s9_dcbhz_bw_d0_g86_i1_sh
I'm sure you can source them cheaper though. This kit just gives an example. But don't forget some additives, carbs, sugars, fulvic, humic, sea weed/kelp, and benny bacteria to breakdown...