hmm im unfamiliar with grow big but i had just assumed it was a high n fert without trace elements in it...i personally hit mine once a week if you go with every other watering depending on heat and pot size that could wind up being every 3 days could be only every other week....so i just stick to about once a week but thats just how i like to do it..
update from this morning biggest plant is geting worseView attachment 2225812View attachment 2225813couple of the leafs now like second pic