Trouble one month into flower, Asking for advice!

[Qanzilla]

This is my second grow. I'm one month into flowering and ever since I flushed with Fox Farm's Sledgehammer, at the beginning of flower, my leaves have been drying up from the tips inwards. It looks like nute burn, so I've laid off nutes for the past 2 weeks and just gave them a good olde fashion water flush last night. No improvement yet.


SOIL GROW

Strain - Pineapple Express/ Blueberry
# of Plants - 5
Grow Type - Soil
Grow Stage - 1 month into flowering
Bucket Size - 5 Gallon
Lights - 1000w Hotilux HPS
Nutrients - Fox Farm full line
Medium - 75% Pro Mix Organic soil 25% perlite
PPM - No meter
PH - 6.5
RH - 25-30%
Room Temperature -70-74 F
Room Square Footage - 3'x3'
Pests - None Known

Problem: Leaves all over plants taking heavy damage. Starting at tips, turns yellow, then moves inwards along veins, then turns brown and eventually falls off. First signs appeared after flushing with Sledgehammer. Have given no nutes since, so I just flushed again last night.




Thank you in advance for any information! I'd hate to lose this crop.. the first round went so perfectly!

 

[Qanzilla]

Last night I fed them some 1/2 strength Beastie blooms and Grow Big by fox farm, because they look to me like they are having a P deficiencey.

They seem to have improved a little bit.. Which is a relief because I thought they were already nute burned, so I was hesitant to do it.

Before feeding I checked my soil PH with a meter and it was reading almost 7.5! I will be feeding them 1/2 strength nutes and keeping the PH low for the next weeks. If anyone has advice for me, please feel free!
Thanks