I wasn't looking forward to soaking these because I tried it once before with a commercial enzyme-based cleaner and it made a big mess in my yard but had no effect on the filter pressure.
I've had the same experience with the cleaners and with muriatic acid; a big mess to clean up and not much improvement in filter performance. The only luck I've had is removing the filter, as waterbear has said in another post, before the pressure builds up and thoroughly cleaning it off with a garden pressure hose.

I do what waste said to do. I usually have two to three that don't work very well that I use for heavy loads and a new one for getting to "pristine condition" - although I've had a baquacil pool and that's been difficult to do. However, I'm currently converting to chlorine. I also find that if I let the old ones thoroughly dry out over a week or so, they regain a little capability. As I throw one out, I get a new one.