Leaves droooping and floppy

Hi all
Newbie here, nice to meet you all!
Indoor grow
Feeding once a week
4-6 weeks old
Canna terra plus proffesional.
Led full spec
Autoflowers.
Leaves at edges drooping at top and slight yellowing at top of some leaves.
Just using water and no nutrients.
Any ideas please ?

How often are you watering? Looks like too much

Slight yellowing and patchy pic.

Once a week .but fed them twice in 3days as thought might not feed enough.soil feels not to wet but not bone dry .

It looks like it needs nutes and a moisture meter to regulate soil moisture.