You haven't said what you're doing when you take clones. Just that you're using rockwool. How big are they when you take them? Are you using a rooting compound? How are you preparing the rockwool? Do the leaves just slowly die and shrivel away or does the stem start to rot? Somewhere something is going wrong and switching methods may or may not fix the issue. I'd look for the root cause of the problem. If you provided a quick step by step of the process you're following someone might be able to tell you why you're not successful cloning in rockwool.
Oh, and if you make a DIY cloner I would use plastic tubing like they do here. When I made mine I screwed around with PVC but if I had to do it again I'd just make a loop with plastic tubing.
For example using rubber tubing instead of PVC.
https://www.instructables.com/id/EZ-Cloner/