HansGoatanswered grow question a year ago High bro, I can see that your plants were still doing great 3 days ago so this is a complete nutrient block.
The only explanation for these symptoms so fast is a wrong pH range, it can cause your plant to go into a nutrient lockout, which means it is essentially in shock and no longer absorbing nutrients for the time being.
You can check the pH and EC from your soil by following these steps.
1. Collect samples of soil from the test area. (The soil should be taken from the same depth below the surface each time you test.) It is suggested to take at least two samples per test. The more samples, the more accurate the measurement will be. Take more samples around your plant and mix them. You will get a homogenous sample.
2. Take the homogeneous sample. Weigh out 1 unit soil (100 g is recommended)
3. Add 2 unit (200 ml) distilled water to it.
4. Stir the sample for 30 seconds.
5. Let it sit for 15 minutes.
6. Filter liquid into clean cup.
7. Stir it again, then take your measurement with EC and pH meter.
Hold the electrode in the sample min. 1 minute before the reading.
When you did this you know how much the EC and pH really are inside your soil.
If this is too much work for you then just flush the soil with 2 times the pot volume in water with the right pH and EC.
Enjoy your grow buddy!