Leaves with browning edges curling downwards noticed stuff on top and under side

[Von Kroppelberg]

Day 45 indoor grow. Just trimmed off these lower leaves and was checking underside and saw this

 

[Von Kroppelberg]

These are the smaller lower leaves. Took them off. Plants had a rough run , mute def then burn then not enough light . Only fixed these recently

 

[CagedApe]

You have aphids for one. Spray with 3% hydrogen peroxide until they are gone. The leaf curl might be due to high nutes.