Frigaultanswered grow question 4 years ago Hi.. frigault here... Coco often catch magnesium and calcium till it is charged. If the coco wasent buffered it takes the calcium and magnesium and hold it and fir this reason cal mag must be added in every feed. Calcium deficiancy look like nitrogene deficiancy but its starts from the too new growth at first... Calcium and magnesim look similair. But magnesium will have the leaf turning yellow and veind remaining green the edge will burn eventually and calcium small spot that looks like rust dots will began.. ph sould be around 5.8-6.0 in coco. So check the ph and ajust the calcium with calmag. Its is very early stage.. no damage done yet