PH meter died - Diagnosis?

[Maryglen55]

I'm trying to figure out what is going on with my plant. Does anyone have an idea? My ph meter broke, so I'm waiting for a new one to arrive (none of the stores sell them in this town!)
Strain - Northern Lights auto flower feminized
# of Plants - 2
Grow Type - Hydro
Grow Stage - vegetative (four weeks)
Setup -Dealzer cash crop hydro box
Light -
Nutrients - General Hydroponics
Medium - organic starter plugs from Dealzer
PPM -
PH - was 5.9 last time I measured (four days ago) I've added plain distilled water since then
RH - 44%
Room Temperature -73
Solution Temperature -68
Room Square Footage - 20
Pests - None

Problem - yellowing of oldest leaves, mid-upper leaves have yellow tips
mottled yellowing of leaves

First Time Grower
Old retired lady, child of the 60's
using the Dealzer hydroponic cash crop system

 

[Maryglen55]

Here are photos from today - again, if anyone can help me with this I would appreciate it so much!

 

[Maryglen55]

My ph meter arrived in the mail today. Ph was 5.9, and I changed out the water with new nutrients and some cal/mag - looks like it might be a magnesium deficiency due to the coloring and the leaves curling up at the ends. Should I add epsom salts to the container or leave it be for now?

 

[Teddy Edwards]

Firstly, to



Secondly, don't panic! I'm a soil man, so cannot offer advice except to say that your Magnesium diagnosis looks correct to me.

One of our hydro experts will be along soon.

 

[Maryglen55]

Thank you, Teddy, for your response! My Ph meter arrived yesterday and the numbers were good (5.9), I did a flush since it had been a week, and added cal/mag and a little bit of epsom salt (maybe 1/8 tsp to one gallon) to the other nutes and it looks so much better today!
Just hearing back from someone is reassuring, so thanks again for replying - for newbies any response is a lifeline and it keeps us going.