Honestly? I just bought a cheap-o ultrasonic cleaner. I tried it on some really old
coils that were super charred up. It seemed to clear the chunks off, but it didn't actually -clean- them.
I've been using rebuildables for 3ish years now, so I don't have much love for coil cleaning. It's faster and easier for me to pull the coil and remake it than it is to try and clean the thing. I use Kanger ProTank 3s, the heads can be re-built, but they're kind of small and tightly packed.
I haven't tried an Aspire Clearo though, not sure if they can be rebuilt.
The ProTank
coils are pretty cheap though, so I will sometimes just buy another pack of heads instead of rebuilding them. (Unless I'm at a B&M....I'm not spending 20 bucks for a 5 pack of coils that I can get for 6 dollars online, sorry.)