Welcome to the farm
Not a hydro guy so i know not much about it there are many who do mind.
Apart from washing the stones before use as said I am not really a hydro guy. hope you have washed them. Might be a good idea to clean the rim cleanliness is quite important esp in hydro
Flip a rock so it’s going upwards more than the sideways it kinda is with it almost leaning on the adapter.
Good luck and happy growing