first ya need more light. 2x20w will give ya around 2000l. Im using 5 23w for 3plants tho ill swap them soon for 4 100w. about the yeld then it allso depends what yar growing. There before christmas i had 4 lowrider x ak hibrids and i fot fck all out of them tho smoke was ari and my last grow i had only 2 blueberrys great yield but smoke wasnt as strong=(