I have now had Aphids on my hydroponic plants in two different cycles. In the first cycle, it took me a while to realize that it was Aphids that were causing the descent of my tomato plant and they were all over it. My choice at this time, because it was so infested, was to take all of the plants out, clean the tower, and try again. In the second cycle I ended up with a small amount of the pests on my spinach, so I looked up a few ideas of what I could do to derail them. I chose a neem mixture, and it worked great. The mixture is (¼ teaspoon dish soap, 1 teaspoon neem oil, and 1 quart of water). You will want to mix the soap with a little bit of the water, then add the neem oil and mix well, lastly adding in the rest of the water and stir, use immediately.
Always test the spray on a small area first to make sure the plant can tolerate the spray. Once you are ready, saturate the leaves, especially the underside, with the solution every other day for a couple of weeks. What is nice about neem oil is that it isn’t toxic to us, but I would recommend that you rinse off the edible plant before consuming it, it tastes better.