How big is the tubing for those dosers? Having a problem with my aqualifter that I use to dose RO/DI water to my kalk reactor, the tubing needs to be RO line tubing to fit into the kalk reactor, unfortunately as I found out last night, it popped off the Aqualifter pretty easily when I was refilling, mostly because the Aqualifter doesn't have a barb on the output it holds on with friction which only works as long as the tubing end remains elastic.
There are some reducers in case the line is loose; one end is bigger diameter.
I was clearing some old stuff and found one little coupler; I’ll check if it fits RO line and air-line tubing.