I've raised the light a couple times lately, but the tops of the plants were never very warm. Playing an IR thermometer against the upper leaves has never given a reading as high as 80° and the back of my hand has never disagreed.
It's hard for me to say how much I've been watering, except that I've cut back a lot the past few days. I've taken to checking for moisture in the medium at the drain holes rather than hefting the pots for an indication as to when I should water. My aim has been to wet the pot through, though I haven't let much run out the bottoms when I do water for fear of too much water (and fertilizer) reaching other pots that may not need it via the tray.
My reading suggests moisture and calcium problems often go hand in hand. Some of it makes me want to try flushing affected plants, but my crystalline shame makes me think twice about that.. I've also wondered a lot lately whether I'm using too much or too little fertilizer. It's been easy enough to follow the directions on the bottle, but I saw something on the website about reducing fertilizer strength by 50-57% for DWC.. So.. is my solution too strong in the vodka bottles? Not DWC, exactly, but seems closer to that to me than coco and perlite in little pots..
What bothers me most is having begun to second guess what little I thought I'd learned. I thought I was keeping it pretty simple with a neutral, well-draining medium, a single complete fertilizer (the thinking done for me, I'd hoped), mixed into the plainest water available, and a plug-n-play light. It sure feels like these problems have come about as a direct result of my not knowing what the hell I'm doing. That's an awful lot to type to have it amount to tautology, lol. I suppose the only good cure for paralysis is sitting still. What say I do like this for the next few days - keep the horizontal fan on 'em, ignore the humidity, quit futzing with the light, and continue watering very sparingly with the slightly reduced nutrient solution? Fighting the urge to flail, here..