If you do darkroom photography you might end up with fixer and wonder what to do with it. Should you toss it down the drain or try to recycle it ?
If you decide you want to try to recycle it, I have two items you might be interested in. One is called a Silver Magnet, the other is a Trickle Tank. Both do similar things but they are quite different
The Silver Magnet is a small device you submerge in a container ( non metalic ! ) of spent fixer. It can’t be fixer that was used once or 2x, or even fixer that “hypo check” said was “spent/used up” but it is fixer that has at least 50 parts of silver / million ( .5 g / L ) or more silver. This means if you do the “clip test” 2x the “clear to film base” time for a scrap of film in daylight, or using a silver saturation test kit to determine the amount of silver in the fixer. You plug the magnet in, you submerge it in the container and the silver electroplates onto an electrode. There is some silver left afterwards, but some of it is extracted
The “trickle tank” is a bucket that slowly drains into a 2nd bucket filled with steel wool. The silver is removed from the spent fixer, by trading steel wool “ions” for silver “ions” and by the end of the operation very little silver remains. Unlike the Silver Magnet, any used fixer can be dumped into the trickle tank, even wash water, and it is “scrubbed” so a level that is very small.