I'm about to sell an old 128GB external SSD, and I've read various guides saying it's difficult to be sure that data is erased when using traditional zero-fills etc.
I'm on Mac OSx, and I got the idea to use Final Cut Pro X to generate very large uncompressed video files of junk (just a plant in my window), and export them straight to the external SSD. A 2 min video clip resulted in a 35GB 1080p, uncompressed, video file! So 8 minutes should be enough to fill the drive, without using any duplicate data.
This sounds like it should be bullet proof, but there always seem to be unexpected "gotchas" when it comes to erasing data, especially on SSD's... Is this method enough to remove any previous data from the drive?