Yellow markings on plants leaf! What is it and can I cure/prevent from worsening?

[Peocash7]

 

[Red Eyed]

Would need some info on the grow....medium used, nutrients fed and how often and so forth.

 

[Peocash7]

Would need some info on the grow....medium used, nutrients fed and how often and so forth.

Coco70% 30% perlite mix
Canna start PH 6.5
Feeding them 3 times a day morning midday before bed
6 hours off 18hours on.
I’m a new grower so you’ll have to bare with lol

 

[Creature1969]

Drop the canna start and move on to regular feed.
PH between 5.8-6.0. Keep that coco wet. It's already too dry. She's old enough for full watering.
RO or TAP water? Adding calmag?

 

[Peocash7]

Drop the canna start and move on to regular feed.
PH between 5.8-6.0. Keep that coco wet. It's already too dry. She's old enough for full watering.
RO or TAP water? Adding calmag?

Right dropped the PH, Coco is wet and tap
Water? Just given them their first feed of Canna A-B? I’ll get cal-mag tomorrow ? Anything else you recommend thanks for you help btw