I like to use Azamax myself. It is not the best at wiping out the bugs but it does work on most of the leaf and root munching critters. The key to it is to first clean up every bit of the grow area of leaf matter as that draws the critters. Then mix up a dose and do a drench and/or add it to the rez. THEN after about 5-7 days(when you don't see it in the water anymore) do another dose and run it a second time.
The second treatment is a must to eliminate the buggers, otherwise you just knock them down for a while then they come back hungrier. The good thing about the Azamax is that it biodegrades within 10 days of use and leaves no residual chemical in the plant to hurt us or the plant. Don't use malathion as that is a potent pesticide that I wouldn't want to smoke as it is very slow to biodegrade. Good luck