Best medium for starting seeds in Aeroponics?

Hey guys,

The title says it all really. I have a 20 pot X-Stream Aeroponic cloner that I'd like to germinate some seeds in, it comes with cloning collars that are about 1/2 inch thick, which obviously won't get the seeds wet or support them for the first week.

What is the best medium for germination? Rockwool? Compost Plugs?

Many thanks.

rapid rooter that is split in 2. once you get roots try to remove the seedling from the plus as gently as possible. I run no media for my plants after that. Just throw them straight into a neoprene colar and put her in veg. Works for me in my DIY aero.