HI TO ALL. YOU HAVE ALWAYS HELPED ME BEFORE SO THIS SHOULD BE EASY. I GROW IN A TENT WITH BUCKETS AND WATER FLOWING INTO THEM FROM RESAVOR BY PUMP WHILE THEY DRAIN OUT OF BOTTOM OF BUCKET BACK INTO RESAVOR. GOT AIR STONES IN BUCKETS AS WELL AS IN RESAVOR.
PLANTS ARE 3 WEEKS OLD AND ARE COVERING LID OF BUCKET. A LITTLE OVER 6" HIGH. WHEN CAN THEY GO TO 24 HR. OF LED 400W. GROW LIGHT. ALSO WHAT SHOULD BE THE PPM. AND PH. AT THIS STAGE.
THANK U VERY MUCH. SAM
G’day sam if they are auto flower you can keep them under 24 hrs as soon as the seeds crack.
If they are normal or fem seeds it’s advisable to keep them at 16-18 hrs for veg 16 hrs of light for normal seeds is said to better your chances of more females.
Switch them to 12-12 when you want them to start flowering.
Auto flower can be kept under 24 hrs of light for the whole grow to get maximum potential.
Hope this helps.
Happy growing! Brendan.
It seems you might have your light schedule ideas backwards? Depending on the strain, most people start with 24 hours of light per day, especially for autoflowers. Regular strains start with 18 - 24 hours of light per day, some people will use 16 hours of light per day. Then when you want the plant to start flowering, usually when it/they have grown to fill about half the space they have to grow they are switched to 12 hours of light with 12 hours of uninterrupted darkness to start the plant flowering. This is the important thing to understand, 12 hours of uninterrupted darkness is what makes the plant flower, most strains need about this much, however some can flower with as little as 11 or maybe even 10 hours of uninterrupted darkness, especially outdoors, indoors most people just assume 12 hours of darkness and use this increment. PH should always be around 5.8 for hydroponics. PPM might be dependent on type of nutrients you are using and your starting PPM of your water, but usually around 1000 ppm is good.
I hear ya MacG! 
Brendan. Nice answer. Looks like you have been studying. Thanks for helping out. Same answer I would’ve given. Peace
HEY GUYS THANKS ALOT. HAPPY HOLIDAYS.
SAM.
Thanks, Latewood yeah I’ve been studying hard! I’ve been going thru all yours and MacGyvers posts and I am learning alot! Makes me realise how much more I’ve still got to learn! It’s all very interesting so I am trying to read as much as I can on the subject, I want to grow the absolute best weed I can and attain the largest yeild possible with my current setup, even in this thread I’ve learnt a few things!
Looks like im gonna adjust my ph level a bit as I have always had it at ph 6·0, I will be aiming for ph 5·8 now on .
Thanks once again! Brendan.