BTI or bacterium thurginesis isralius. Commonly called BT or mosquito dunks. The liquid is better. You will have to treat more than once. Sticky traps will catch some of the adults. Somone may know a chemical method
ive been treating with gnat off, seems to have helped quite a bit, killed lots of larvae off as far as i can tell without diggin into the coco hehe, definetly hardly any flies knocking about now, just gonna have to treat em a little longer
im into bud now and just hope they are gone/under control enough
cheers