It is, as organics beak down the release amonia, raw shrimp just happns to break down easily, is commonly found everywhere and cheap so it makes a good choice. I prefer to dose ammonia from a bottle, but eithr way gets results, dosing is immediate whereas the shrimp needs time to break down.
With 100lbs of lr, youll probably have 0ammonia, 0 nitrites, and nitrates climbing fairly quickly. Get yourself a test kit (if you dont already have one) add an ammonia source and test. If using the shrimp method like 2-3 days after you add, if dosing wait 1 day.
Dosing ammonia can reqire some math because you dont want much more than 5ppm. I have the math in a long forgoten thread and saved on my comp but not handy atm. Ace hardware janitorial seems to be the prefferred stuff. No surfactants perfumes or dyes is what to look for. Adding a tiny bit and testing after youve let it mix is a good option as well.