Here is the most likely cause of your issue. Not pH ing the water is the problem!
If you are using tap water and nutrients there is no telling what the pH is and it is harming your plants!
You need a pH meter or at a minimum a ph test kit, ph up and down and calibration fluid. Here are some options.
Apera pH Meter
ph and tds meters
ph meter only
pH Test drops 1 ounce
ph up & Down with test kit
7.0 calibration fluid
You can also get ph testers and ph up and down at your local pet stores that sell supplies for fish.
I would recommend not giving anymore anything until you have properly ph’d your water and nutrients.