Necrosis, older+middle leaf yellowing advice sought

[Clem Fandango]

G'day.

Two plants getting close to the end. They have had a hard life due to my new grower mistakes.

Medium Coco/Perlite

GH trio Lucas formula. Don't have ppm/ec pen yet.

Schedule= feed - feed - feed - water

Calmag only recently at 2 ml per gallon every second feed/water

PH'd water at around 6 sometimes up to 6.2 recently but most of their life at 5.8-6 @ 1.5 gallon every two days per plant.


Pictures Show some progressive necrosis and yellowing seems to be getting worse.

I read a bit and it seems to be a calcium Magnesium deficiency, is 1-2 ml per gallon too little?

White balance of pics is all over the place in the bathroom.

I've given them two days off feed water as humidity was high here and they weren't uptaking the water as quickly, they are thirsty today.

 

[Clem Fandango]

Ok,so just gave them a weak feed and a Calmag solution at around 8ml per gallon. PH'd to 6

What I also did was measure the pH of the runoff it came out at 5.2.

So my intentions, until someone tells me otherwise, are to wait a bit and flush through with water at pH 6.5 until I can bring that run off pH up.

The reason I am going to wait is that run off measuring isn't really that accurate but gives me an indication of where problems may lie.

If I see an improvement in the plants over the next 24 hours I'll not flush with water but instead continue my schedule with an increased dosage of Calmag and have the pH of my solutions sit around 6.5.

If this is erroneous thinking please chime in.