Mottled yellow spots, leaf damage

Hi all im a new grower this is the first time ive grown anything so im sure this is my error ive read a few books but still cant figure this out. Everything was going great then these yellow/brown spots started at the tip of the bottom leaf of the largest plant and drys out the leaves into a taco shape and now its doing the same to other plants any suggestions will help.
-temp 68-78
-humidity is a steady 40%
-ph 6.4
-hydro drip system over a dwc
-floranovagrow2tps/and flouralicious1/2tps to 4gallon resvoiur and 1gallon backup
-400wat hps 2.5 feet from top of plants

im having to go through the same shit ure going through but i think with a bit of flushing up the plant with distilled water (or reverse osmosis water) i managed to regenerate the plant cause the new leaves appear dark green not pale green and have a great weed smell( the pale ones had no smell at all)
hope it woulod work 4 u mate

Yeah I w9uld just say flush them and dont worry about it untill the problem is most of the leaves I dont worry about it if its just one or 2 out of a good plant

dude, hydro systems need a ph of 5.2 to 5.8 and definitely not over 6..... that's your problem..... the nutes are locked out, it's a nute deficiency..... take care of the ph and you should take care of the problem..... the affected leaves wont turn good again, but you shouldn't see anymore leaves turning that way.

ORECAL said:

dude, hydro systems need a ph of 5.2 to 5.8 and definitely not over 6..... that's your problem..... the nutes are locked out, it's a nute deficiency..... take care of the ph and you should take care of the problem..... the affected leaves wont turn good again, but you shouldn't see anymore leaves turning that way.

Click to expand...

from what I saw in his pic he was growing in dirt and all he had was a drip over them.

for the record it was a lack of mag because my ph was off...classic noob mistake...always check ph!!!!!

lack of cal not mag