I was doing so goo!!! Wtf is happening???

I have plants about four week old in 3x3 rockwool cubes, For the most part they look pretty healthy.

The root tips on the bottom of the cubes have started to look burned??

I recently upped my PPM to full Streangth Vegg per CANNAS online feeding chart, I am at 650 PPM With RO water.

The roots look VERY healthy the last time I looked at them, before the last nute batch change, I was at 520.

I see no real indication of nute burn in the leaves.


WHAT SHOULD I DO????

Keep on as normal until I see something in the leaves?
Flush the cubes for a good bit with RO water?

IF YOU NEED ANY MORE INFO TO HELP PLEASE ASK!!!

THANKS SO MUCH STOPING BY AND SHARING YOUR TIME AND KNOWLEDGE!!
Flush and feed at say 600 ppm? 650?

Or are they being "air pruned" and I should go ahead and transfer them to the slabs?


When do I need to transfer them to the slabs?

I was doing some research, I have also come up with the possibility of needing to water more frequently,

Currently 2 hr after lights on for 2 min, once mid-day for one min, and once 2 hr before lights off.

CURRENTLY IN VEG.

Should i remove " a minute" in the morning and add that minute somewhere in the day?

Thanks

Air pruning. Transfer to solo cusps