Removing orchid from soil to s/h

[10acgal]

Hello, newbie here. I recently purchased a dendrobium kingianum that had been potted in potting soil. It needed a repot badly and I also saw some small black bugs in the top of the soil so I decided to go ahead and put it in s/h. The problem is I cannot get all the potting soil out of the roots. I currently have it soaking trying to loosen it up but after an hour it still is not coming clean. I've never dealt with potting soil before, just bark or moss. What will happen if I put it in s/h and it still has the soil? Will it cause rotting? Help!