leaving them submerged will rot the stems. they need to breathe just like the root system does. what ever you use as far as pellets or rockwool, make sure the stem is snug with the medium to get good root growth.
Ok so I only had 1 successful clone out of the 7 or 8 that i took from the crystal plant and put in water.
But I just went out of town for a week and before I did I built a little bubbler cloner. Took a bubble stone and pump that would go in a fish tank, got about a 9 or 10 inch deep long thin container with a snap on lid. Filled it up about 6 or 7 inches high with water, peroxide, and a small amount of bloom nuet. I put several inch round holes in the top (big enough to fit roots through) clipped my clones and put some cloning solution on them (was very careful to not let air in stem). Then I put a strip of tape over all the holes, poked a hole big enough in the tape to barley fit the clone in. I suspended them about an inch above the water and turned the bubbler on so that water gentaly misted the stems all the time. I got home today and out of 6 clones 2 have roots and the others look like they wont be far behind. I think I have my new method. If anyone needs a picture of my system let me kno and ill see what I can do
GIVE IT A SHOT!