curling leaves

hi one of three plants has went like this any ideas

5.8ph
temp 25-26
55% humidity

looks like its really hot

haha mate,
i had the same problem, i have told about the problem in my journal...
well wha water u using, because mine was overwatering as well using direct tap water,
worked on those and she was absolutely fine...the left remained curled but the new growth was healthy.

eyecatching avatar btw