I've had good results spraying a tea-infusion made of garlic, lemon juice, onion, chilly on the leaves.
I used 500ml boiling water, 2 garlic cloves, a squirt of lemon juice, chopped onion and chilly. Mix together and let to cool to room temperature, strain and spray/mist the liquid on the leaves.
It worked for aphids/ants on tomato, salad.
I made garlic and chili yesterday and spayed them last night, when I checked this morning they're still on the leaves not sure if they still alive. Anyway, thank you I'll try that one too if I cant see any improvement.
Ok - then it's time to bring out the big guns - more information here http://brightagrotech.com/pesticides-for-aquaponics/
Thank you for this helpful information Pieter.