how strong is the light your using? is it new to this light and area? she seemed fine last week and youre right that its only near the light. she may just not be used to tbe intensity?
also idk about vinegar as a water additive. have you had experience with this? i feel like the acidity would drop the ph wildly at the soil level.
try using just plain water. i boil my water and then let it cool and it seems to work fine. i don't ph anymore as long as the plant is happy and they have been with dechlorinated water via boiling and cooling
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