First time bubbleponics .. whats going on with my plants????

Hi ppl , ive been reading a fair bit on this site its become my bible lol
But i want to be sure on this as i cant get clones so I hope someone can help me out..
this my 1st time using bubble ponic method, the clones i got i had to re vedge from lil budds but i managed to do it , i have got a home made light diffuser on my 600 light and its up high atm ,i havnt got a ec tester atm but the nutes say 4ml a liter i have put half the recommended dosage in atm and my water level is just under the net pots with the roots dangaling in the water.
As you can see in the pics the leaves have yellow bits all over them and sum tips are curling some are drooping and sum leaves look burnt?? i broke my ph tester the other day have a new one coming soon but ph usaly stays between 5.2- 6.2
Any help would be awsome i want to fix these girls up

soooo aNYONE got any idea's?????

3 dayz still no help awsome!

I ll give it a go. Im not an expert but from what I ve read its still to young to start nutes. Also have you checked the roots? Any root rot going on? How your temps? Like i said Im just starting out but from what I ve read that seems to be the problems. Hope all goes well

Thanks for the input bruz,
I think I got mas nutes burn,i flushed for a day then got a new ec and kept it,low this time
I,lost sum leaves but there recovering