DIY cloner question

So im gunna make a 6 site bubble cloner with a 1.5 gal container. i dont have pics.

im wondering how man liter/minute im gunna need to get enough bubbles to start roots. i have an air pump but its from like 1970's and a 6in air stone i got from wal mart. what else do i need? and how strong wud the pump need to be?

I would say one rated for a 10 gallon should more than do ya..and I think they are the cheapest ones at walmart...so have at it...

do i put the stems slightly in the water or just above it?