i used to use very small cuttings 2" or so and found they root allot faster than larger ones. also i kept my bubbler in my vegg chamber about 24" from the 8 4ft flouros any closer and the leaves start to yellow long before any rooting begins. you don't want to much light 'cause the cutting will try to grow instead of produce roots and this will cause it to sap all the nutrients from the leaves and that's why they yellow and die before rooting. at least that is how i understand it. btw 1 airstone could work, just put a cutting in and see if it lives to make sure. i'm not growing currently for security reasons(facing felony charges) but i still love to visit these forums and offer any help that i can.