I need to buy a hygrometer, no doubt, but there are much more humidity-sensitive plants (eg nepenthes) growing in the same environment, and showing no signs of burn or wilt. I believe the humidity did drop a bit a week ago, but it's always pretty humid in my growing area.
Temps have fluctuated from around 80 to perhaps 50.
No direct sunlight, just lots of fluorescents.
I was hoping somebody would confirm my suspicions before i revealed this clue, but when i first planted the (bareroot) vfts about a month ago, i used something called "Aquatic Plant Soil" by Schultz that is supposed to be inert and pH neutral instead of sand (which i hadn't been able to find). However, i have heard rumors that this stuff does tend to leech certain mineral salts. I was hoping the VFT burning was something else, but it is possibly due to the buildup of salts over the last month. It was growing robustly until just recently, however. What do salt-burned VFTs look like?