Plant over or underwatered

I am currently growing 1 lowryder#2 and an og kush under a 400w hps. the lowryder is growing really well but the og kush leaves are drooping.
I have given both the same watering schedule, watering when the soil feels dry at the top.
they have been growing for 3 weeks.
Not sure if it has been over or underwatered?

Overwatered.

You should learn* to water by the weight of your container (or at least stick your finger way down in it), just checking the surface of the soil is bound to fail.

What's the temp in there ?
Looks like heat stress IMO

Agreed^^^^^^^^^^
How frequently do you water?
If you pick up your pot, after watering, then wait 3-4 days and pick it up again, you will feel the difference in weight.
Also, another thing I do, since I have outdoor plants, is feel the side of the pot close to the top, and compare the temperature to how the pot feels down lower.
If the temps are close, I know the soil down low is almost dry like the top, but if the bottom is colder, from the evening air, I know it still has plenty of water.

i water about twice a week, the temp is 28c

3 weeks old, maybe you need to give her a bigger home, but how do you determine when to water?