Can you give me any advice ?

I was mashing in a 5 gal car boy and every time I would pitch my yeast within a couple hours it would be bubbling like crazy in my airlock and I would always get a good yealds out of it . I’ve since move on to using a 30gal foodgrade plastic barrel with a clamp lid I’ve kept my recipe the same just multiplied it and now when I pitch the yeast it never really works off as well in the air lock and I’m not getting near the yeald.