You need to make sure you completely drench the root ball. A good way to do this is by putting the pot in a bucket and covering it in IMID solution. That will kill them for good. IME, the aphids slow the plants down. They eat the root nubs off of your clones so your clones never root. The IMID has an effect on the plants as well... So they don't just have to recover from the aphids, but the IMID as well... And that takes the better part of a month. Like i suggested, you might want to get some new clones or crack some seeds while you get your plants back to health. I don't cull a good plant unless i have to...