i ran out of perlite

can i mix in gravel as a substitute ¿?

you could go buy more perlite

perlite is like $4 a bag bro...

damn, i was just curios if gravel would work to. i plan on picking up another bag

Toss a bit f perlit into a glass of water..... It floats, it's made to airate the soil.

Toss some gravel in a glass of water..... It'll sink, it won't airate the soil so much....
I'd just get another bag of perlite if I was you.