cheers bud youve been a massive help, i was wondering how long after the transplant should i leave it, to check if the roots with soil around have rotten? i dont wanna stress the plant too much by taking it back out of the clay pebbles. and how far up the net bucket should the water be, should i be trying to tease the roots downward with less water or making sure some of the roots are submerged so their 100% getting what they need? thanks again
The roots in the net cup itself, in the clay pebbles will stay good longer, and may actually adjust, than the ones that are actually submerged. I put a few pebbles in the cup but don't cover the bottom so I can slowly lower some roots through the holes, pull them through if needed. Those will be submerged and will be able to take up enough water for the roots that are in the net cup (besides the high humidity in the net cup already, make sure it's closed, i.e. dark). By the time those submerged roots will go bad, the part in the net cup should have spawned healthy new white roots. It's a shame I don't have a good picture, I transplanted some a while back, but you will clearly be able to tell the difference between the new hydro roots and the old ones. Besides white, they will be separate from each other (like the roots sticking out of a rockwool from a newly rooted clone).
Ideally you let them get used to being in hydro gradually. But I think the best approach is to count on them going bad (rotten is big worth, they will die before rotting). The problem with transplanting to DWC from a medium is that the roots will stick together sort of blocking themselves, while in the medium they were spread out. You probably noticed that already when washing of the soil. The more bubbles you got going on, the less that's going to present a problem. Also the more roots you cut off (depending on container size obviously), the less that is going to be a problem as well.
Make sure you keep the nute solution temp low (below 68 ideally), even more important with a transplant than it is in DWC already.
Good luck! And don't worry if some leaves turn yellow and die off, as long as it starts creating new roots it will likely survive.