Overwatering or something else ?

I am on my 3rd grow and luckily I haven't had too many problems so tell me what u think ....

Is this plant showing signs of overwatering ???

Whats your temps??

20 dgrees Celcius lights on
10 degrees Celcius lights off

It is a bit cold 20 should be your low when lights off how often do you water

looks fine as far as watering goes if you ask me. it looks like its getting burned though

Maybe lights too close???

are the curled up leaves dry?
the best way to tell if you're over/under watering is to get one of those water testers. it looks like a probe and stick it down in the soil... if its still quite moist down to the middle and bottom of your pot then you know you're good to wait another day before watering. to me the damaged leaves look like it could either be a) underwatering or b) light to close to your plant.