Leaf colour

Whatever it is to fix it you need to give ph water only to start the diagnosis, watch and adjust. Cana coco is a good feed so maybe wait a week with just water then start by giving half strength possibly 0.5ml per ltr and watch, if it gets worse add calmag at 1ml per ltr amd watch.. they look healthy apart from the chlorophyll production in the leaves.

More than one thing can cause chorosis and Mg deficiency should come with rust colored spots too. Properly buffered coco should not leach any Ca or Mg. That is the basis why it often gets repeated that coco 'needs more of...' but really if it is true is just a sign of a shitty manufacturer and a reason why coco is not the best medium to choose. Poorly processed coco will derail an entire grow - severe delay or even death. canna coco comes with a pre-charge of nutes but that will quickly run out, so you can think of it as 'soilless' and you should treat it that way. It needs a full and complete diet provided with every fertigation and 10% runoff to avoid buildup of nutrients in the medium. Don't let it sit in its piss either. that runoff is fine for an outdoor garden but not for potted plants, if you don't want to throw it down the drain. So, i'd double check pH is somewhere in the vicinity of slightly acidic and maybe wait a second longer to see if other symptoms present themselves that makes identifying the cause easier. If it isn't a mg-deficiency, then adding a bunch of Mg will possibly cause more problems. While less likely, could be related to deficiencies of Mn, Zn or Fe. When you see these symptoms it's usually a matter of nutrient balance or pH rather than enough being physically present in the medium. A soilless fertilizer regimen should have plenty of trace elements. For soilless/hydro, tracking ppm of each nutrient or the weighted average of percent of mass from the labels really is useful. You can avoid nearly all problems preemptively by doing so. Problems become so small and slow-moving that it takes months to show a symptom.. then you tweak a bit more and avoid that, too. "Aim small, miss small."

Why would it be a magnesium deficiency when he's adding calmag? Potassium deficiency is what I would guess and they look pretty similar . Since the ladies are young, pretty dark green (too much N hinders potassium uptake, as well as too much calcium) and already getting calmag without being in bloom, I would flush with half nutrientsolution.Run off should be around 6,5.

Hey bro, that’s early mag deficiency, common with coco and osmosis water. Your CalMag might not have enough magnesium for what coco steals. Up the CalMag a bit, or just add a pinch of Epsom salts 0.3–0.5g/L Keep pH around 5.8–6.0 Nothing crazy, they’ll bounce back if you fix it now. 🤞🍀♥️

Magnesium lack. Epsom salt around 100ppm extra to your base feeding. Should sort out quickly.