Ahh ok...I can't pull the trigger on a auto feed system. Plants look hella happy. What strain? Mine get a liter'ish a day about two hours after the lights come on.
You don't get rid of aphids...you manage them. Then take a grow break and clean the fuck out of everything and learn from your mistakes. Quarantine everything that comes into the grow area and keep it clean
The ppm's could be lower with this because its chalked full of mycorrhizaes and microbes. All that buffer in your root zone uptakes the nutrients more efficiently. So you can get away with feeding lighter.