Diagnosing a plant in organic coco

[Grovegrows]

Hello I am growing in a mixture of perlite canna coco coir and for nutrients I am using earth dust dry amendments. My plants have been droopy lately and I have barely been watering to runoff how do I dianose this plant just water to runoff and test ph and tds? Or is that just for synthetic nutes? Sorry total noob first grow.