Bottom line is you're unlikely to eliminated the aphids once you have them inside. With fewer plants than I grow now, I've been effective by simply taking the plants to the shower every several days and either spraying them off with the shower head or inverting them into a 5 gallon Home Depot bucket (plain tap water in each case) and agitating them to remove the aphids. I do this every several days over a few weeks in an effort to catch new aphids that hatch before they reproduce, and then again when they reappear - they always seem to reappear after winter and before plant-out time even when they plants have remained inside. I've successfully gotten batches of overwinter plants to plant out this way, but only when I had manageable numbers of plants.
The problem with seedlings and young plants is they aren't strong enough for sprayed water treatment nor do they stand up well to soaps, oils, and other treatments. Plus it takes minimal aphid predation to kill them or significantly retard their growth, often permanently. If the aphids get into the nursery, it's an extremely bad situation and I'd be seriously considering removing all inside plants and starting over. What's crappy is that you basically did get rid of your plants and start over and still somehow they came back. I've never had that happen to me and it shouldn't happen like that.
i haven't spotted any on the seedlings yet, i moved the potato plant away from the seedlings and put the plant under its own lamp, a bit royal for 1 potato. but probably better then letting it spread to the seedlings until ive done the spray/wash method for couple weeks. if it continue to appears i guess il just get rid of the potato as id rather get my chilis back to producing fruits again then growing potatoes.
yeah i threw away 3x 2 years old chili plants, put em into bags and into the garbage outside so its weird, are aphids able to survive in soil for months or even weeks?
ive never had this aphid issue before until this summer when i put all my plants into a greenhouse for the summer, once i toke em inside i spotted hundreds of them on my plants couple weeks later, before this i was growing indoors only and never had any issues other then edema. but wont stop me from continueing as i have a second greenhouse on the way for a bigger potato,onion,carrot farm.
i can spot few aphids that i squeezed by my fingers on the potato just recently after posting this so the spraying havent worked 100% but defiantly removed some of them so il just continue to try to fight them.
With the depot bucket, do you hold the plant upside down and dip the plant into bucket of water or how does that work?