I don't really know too much about the air pumps I'm new to DWC myself but I used a very small aquarium pump like 4w at beginning and when I switched to 25w vivosun air pump it made a world of difference it was amazing.
I use apera ph60 and ec60 after breaking both my cheap pH and EC metres. To me the plant looks over watered which in hydro would mean not enough oxygen by roots?
It looks similar to my first plant I grew with a weak pump but idk