Correct, yes 48 lpm. I used those medium sized air stones but found they put out much bigger air bubbles, so I made my own DIY air diffusers with 50’ of Dramm 1/2” ID soaker tubing with each:
4 - 1/“2” Tees,
1 - 1/2” Cross Tee
1 - 1/2” to 1/4” Reducing Tee