Uknown Leaf Issue

So i have had this issue since early veg and i am now one week into the switch. It happens on the lower older leaves at first, im thinking its Fungi of some kind ?

Coco Perlite 70/30
H & G A + B
Bio Diesel Marine CaMG+
Roots Excel
Drip Clean
EC In = 1.3 EC
EC Out = 1.5 EC
PH In = 5.8 / 5.9
PH Out = 5.9 / 6.0

Over watering

I have been told watering up to 3 tmes a day is fine, My roots at bottom of plant are bone white.

Try pouring water S L O O W L Y.
Inconsistent, uneven and willy nilly doesn't get it.
Do you pound a 40 oz drink in 1.3 seconds?

I agree with over watering. Your plants have to be drinking that much to be watered 3x a day and be alright. Doesn’t seem like the case here. I don’t grow in coco.. but opinions seem to be slim.