That's bad for 2 days. Never seen a fungus take over that fast at 68 degrees. The lower temps should slow it down. looks like you need to clean the system with H2O2 real good. If it's your clones what do the roots look like ?

I'm lookimg at the merit 2f. and since you have the rez I would say an ebb and flow table ? What would make you think you had root mites ? never heard it brought up in hydro. Looking at it , it is for turf grubs and very poison. Not some thing I would put in there. Did this start befor you put the merit in ?

How do you know it's root mite to start with ? Please some pic's of plants and roots.