Again, what brand of coco did you use? Its possible that if you didn't wash it properly before use you could be overdosing with a salt of potassium and the coco could just be sucking up the calcium and none is getting to your plants. I might consider a light foliar spray with the
cal-mag extra, and that is one nutrient you could use at full strength. I have been doing my
cal-mag feeding separately from my base nutrients in my coco grown plants for the last few months, I think that has proven to be of benefit to my plants; it may be something you consider doing as well.
As for the volume you are watering at make sure you are seeing some run-off from your pots; while coco does hold a considerable amount of water they also hold a ton of air so heavier waterings are not going to do damage the same way it would in soil. So don't be too afraid to water regularly.
Ultimately I think your nutrient balance is off and that is what you are seeing with your plants.
Also 71 degrees is a bit low, with led lighting you want the lights on temps to be above 77, I like to see 80 in my tent. Also you may want to get the relative humidity up to 60%. I think adjusting these parameters will also help.