But you are still giving the plants something in the clone res, no? Its not like its just straight PH'd RO in there.in my experience a healthy mother is a must. Low intensity light would be next.
IMO, nutes while trying to root is counter productive, you want it to root ( hormone change), not grow.
Yellowing comes from the plant feeding off it's self while trying to grow.
I find using an aero cloner (Clone King ) is pretty fool proof.
I run perpetual, & can reliably count on a bushy roots by day 14.
good luck