It's not a heat issue.

Do your nutrients recommend thet you feed the ladies every day...? Usually, the application/dosage rates are for a 1 week period.

Coco retains salts, creating a build-up. A flush with properly ph'd water every once in a while (every few weeks or so) is recommended.

Humidity is a tad high for my liking.

What are you using to adjust ingoing water ph?