yellowing and burnt edges

[dieseldawg2480]

Started noticing some yellowing and burnt edges on upper mid leaves. The lower leaves are starting to rust, and droop. Im running a dwc H2O@ 67, temps 86-90, humidity 50-65%, co2@1000ppm wk4 of flower. 2ml/gal- cal/mg cultured solutions total ppm 550-700 500scale ph 5.8-6.2 having trouble keeping it to stay in the 5.6-5.8 range always goes up to low 6's ppms are dropping daily, drinking 10-15 gal of plain h20 from auto fill rez daily. please chime in and ask if i forgot something thanks

 

[MysteryChild]

Looks like they need a little more potassium
Ph fluctuation can cause lockout of nutrients
Try stabling your Ph first
If that doesn't work raise your potassium levels

 

[Seamaiden]

And/or less N here, too. I've never seen yellowing of the upper fans quite like that, though.

 

[budfarmer]

looks like some thing I have been fighting and still don't know wtf , my guess is your ph swings are causing issues just as MysteryChild mentioned. What nute line are you using ?

 

[dieseldawg2480]

looks like some thing I have been fighting and still don't know wtf , my guess is your ph swings are causing issues just as MysteryChild mentioned. What nute line are you using ?

I'm using cultured solutions. Just under what the recommended nute schedule. 2ml/gal cal/mg