red color on new growth

She looks to me like she's got a nitrogen toxicity - further evidenced by the fact you say you detected a calcium deficiency... you've given her too much nitrogen which has caused a lockout so that she's not able to access the calcium she needs - wouldn't matter if you gave her a whole bottle of calmag, she couldn't get at it. Flush her out and when you feed again, make it only 1/2 strength and cut back on the nitrogen-heavy nutes even going forward. I'd even advocate for a slight increase in your pH to 6.0 to help with the absorbtion of calcium... that's a perfectly acceptable pH in coco... I just think you're really overfeeding her right now and she's trying to tell you she doesn't like it. Red stems are definitely a sign of high stress... flush her and go easy on her! Good luck