If it is very sick you might have to go back to 18 hours of light for a few weeks to let it re grow vegetive. Keep the pump working properly and do away with the air stone completely. Use oxy plus to kill any pythriums.
Hi,
you need a product called PK 13/14 it will double the size of your buds. Please bear in mind that if the buds get bigger the plant will need to make more resin for them. Pk 13/14 is used in small amounts and 1 litre is under 15 quid. I can get for you I own Andover Hydroponics or...