Phal and dendros root fungus and root rot

[Nimpa]

Ok so I have a lot of root problems. And I'm just going to list them

-2 phals I cleaned of from dead roots a few days ago and potted loosely. Today I found out they smelt very very bad and I take them off rom the media and behold the roots smells bad. A lot of the roots were dead.

-one phal got white fungus on it roots and I've been airing it out but the plant is now shirevelling because of dehydration.

-a dendro also has fungus problems and I notice it today

All of them were brought without tags. So I have no ID on all of them

All potted in a mix of charcoal, sphagnum, cocnut husk, and fern fibre (we don't have quality bark here. The mixture is what other people use here)

What should I do? What should I do in the future to prevent this?