unknow problem, lower leaves

This is happening to the lower leaves, they are dieing and falling off, can some1 tell me wht it is some type of deficiency or ph problem.

veg 18/6
400w mh
foxfarm ocean forest
foxfarm growbig
filtered water twice a week (when probe shows dry)
food once week, 2tea spoons per gallon
temps 75-80
RH ~40% I know its low
PH, this is where im not sure, soil ph tester shows 6.9,strips show between 6-7 for the water.




edit: been lookin here https://www.rollitup.org/view.php?pg=faq&cmd=article&id=36 Magnesium?

if they are lower leaves than just keep an eye ....... do you mix perlite with the soil?

thats whats happening to me, you may have lock out...i think you should invest in a better Test method, atleast the drops....as for myself i think i have root issues, how old are your plants? when was the last time you flushed?

Looks like a nute def.- N. Possibly from a lockout... Ph'ing ur food?

They are in veg 5 weeks old, just ocean forest 2 gallon pots. I thought the foxfarm ocean forest had a good balanced ph range?

I should metion that till they were about 6in high they were in a miraclegrow mix of peatmoss vermiculite and perlite (6in pot), than transplanted to the ocean forest(2 gallon)

I have been using those thin strips to test the water im giving them, shows 6-7 i kno they are most likely worth shit too. I have too soil ph testers they both show the same ~6.9

Right now i don have a good digital ph tester. I have tried the ph tester with the drops and found it inaccurate. I am a lil short on cash i kno those digital ones cost 100+

sure its not a def. without lockout? i kno its hard to tell.

I use the drops from gh to ph my food, and water. Unfortunately I've recently had to flush due to ph issues from the salts in the ph up in the kit. Those leaves in the pic look deprived of nitrogen, whether from lack of food or from ph lockout idk. But u gotta have an accurate ph reading to know for sure. I've heard nothing but bad about the elctronic meters, the cheap ones anyway. Everyone says they always read at 7. I had a cheapo one too, and it did exactly that.

u mean a cheap meter like this, or a cheap digitial

Not that exact one, but damn close to it. Mine was nearly identical to that on in the pic. Only difference was mine had the two metal probes sticking straight out the bottom. All it ever read was 7.