New root die in S/H

[The Duchess]

Hi guys! I have a small problem with a phalaenopsis. Is in S/H from 09 June 2018 and a new rot die. First grow from a old root, but then stop growing and now is dying and I don't know why... Is become light green/gray... Other new roots seem OK, they growing... But this one I don't know what happend with her..
I use tap water 150-170 ppm, pH 7.50 and I fill the pot to the top when I water. I fertilize with 25 ppm.
I use pelgrom euro pebbles, I wash them how good I can, but steel they have some dust when I use them, water have a orange color from dust. Maybe this clay pebbles are not good for S/H? You have bad experience with clay pebbles who are not good for S/H?

First 2 photos are with that root who dying.

[Ray]

The old root is likely failing, as expected, and cannot support the new growth.

Nothing to worry about, as the new roots will take over.

[The Duchess]

ok. thank you.
Ohh I really hope S/H to work and for me, I don't want to go back to bark...

[SillyKeiki]

If the orchid was in a different media previous to this repot, it is normal for some of the old roots to die, as they are not optimally adapted for the new media. The new roots will grow adapted to functioning in the new clay pebbles, so don't worry as long as those look okay.

At least that has been my experience so far when moving to semi hydroponics.

[fooferdoggie]

yes unless the plant was in all peat moss then it is not as much of a shock since that stuff always seems wet.