yes, I would avoid any coco that has anything in it, even perlite! you want a plain brick of coco, premium brand if possible! but nothing that already contains perlite or lists a single other thing added... you want to start from zero, that allows you full control of what you give to them... coco is so stable as long as your ph is on you will not have an issue. For me, I find 5.98 is like perfect ph for coco, I get the best growth,plants looks super healthy at that ph...