how to tell if my brillo is tight enough?

so it's my first time smoking by myself and not with someone to make the brillo for me. I know you gotta push it back and forth to tighten it. but how do I know if it's tight enough? my rocks only crackle for about a second before they melt. when I used to smoke with my friend itd crackle the entire time I'm bringing the stem down. and how do I tell if it's too tight?