HELP! Top leaves starting to turn yellow compared to lower leaves.

[PrincessPuss]

My top leaves starting to turn yellow compared to lower leaves. First time grow using 2 PuTang clones that we have had for 11 days in a top feed DWC using two 300w Full Spectrum GalaxyHydro LED lights about 18'. PH has been maintained at 5.9 and the PPM has ranged from 780-590 currently. Temp ranges from 74-80 degrees, and 47%-60% humidity. Using Hydroguard, General Hydro Flora Series, and CaliMagic. Have left lights on 24 hours a day.
Leaves are huge compared to the original bottom leaves and look very healthy except that the top large leaves are starting to yellow. I also want to top them but cannot figure out where to top because it seems like there is too much new growth at the top.

[alltatup]

Hi PP, Look over this page and see if you can figure out the culprit: it looks like it may be a pH problem from what I saw on that page. Maybe up the pH or allow it to fluctuate? That could be a deficiency cause by the consistently-low pH.

You top by pinching or clipping off the apical bud site at the top.

https://www.growweedeasy.com/why-cannabis-leaves-yellow

[D.A.A.S.69]

If that doesn't help ,i would raise my lights a few more inches.
I've got a couple of those GHydro, 300s, and they will bleach your plants very quickly,
GoodLuck

[alltatup]

PrincessPuss Listen to what D.A.A.S.69 says, because he's been growing for decades. I've been growing for two years.

[PrincessPuss]

Thank you both so much. I was worried it might be the lights. I will raise them a bit. Thank you again.

[Redwasp]

I was wondering about the distance of the lights. Is 18 inches what the manufacture recommended? My leds, viperspectrum 450s, I keep 24 inches away for the most part. But 18 inches may be correct for you light. So just double check that.

[PrincessPuss]

Thanks! Our lights did not come a manual and the online recommendations are not very clear. The issue is we are already running out of room and need to get a taller tent. I have raised the lights as much as possible and done so low stress training and it seems to be working.

[PrincessPuss]

Thank you to everyone for your replies. They seem to like the small changes and the new water. They are really spreading out after some low stress training and some pruning of large fan leaves.