looks like weird growth, but no real cause for alarm
EDIT: looked at the picture again
not weird growth
Might be a slight burn but looks more like light or heat stress
Are any other leaves curling upwards?
temp bit high 32.5 cant get them down, feeding nutes at about 400ppm my water is at 260ppm. ph was off at 6.7 after rez change and got rust spots and had few black tips on some the leafs.
any idea what the rust spots could be the ph was only off for about 12 hours maybe less would the be enogh to cause rust spots on the leafs?