Calcium deficiency??

[Ryguy]

A few weeks old. Not sure what going on. I've added cal-mag. Maybe not enough. Looks like calcium deficiency to me.
i use r-o water with 600 watt hps. Anyone else have any ideas?

[GreenAlchemist]

It definitely looks like a calcium deficiency, if you’re using R.O water, it strips it clean of calcium, and it becomes a nutrient you need to add to the list of nutrients used.

I’m not so familiar with the topic as I haven’t used R.O water or had a calcium deficiency myself yet, but I’ll included a link to GWE calcium deficiency page, and it will answer almost every question you’ll need to get her back to a thriving green state. Hope this helps some

https://www.growweedeasy.com/cannabis-plant-problems/calcium-deficiency

[gbauto]

Yep, that looks like a Ca deficiency starting.
What are you feeding them?

[ChadWestport]

It does look like a calcium deficiency, what Ph are you feeding at? Calcium gets blocked out by low Ph as well as by high levels of phosphorus.

[Rwise]

Like Chad said whats the PH