What is this deficiency with DWC, GH Trio, flower day 19

Check the ph - it’s too much pk/calmag - I get it all the time less is more 👍 loving the grow ☝️

This does indeed look like a Calcium (Ca) deficiency! with tips and margins developing yellow and brown irregular spots from bottom-mid to top of the plant. This is probably the results of the low pH in the reservoir! low pH (acidic) in the solution or medium inhibits nutrient uptake such as Calcium. Try stabilizing the pH and checking daily for improvement, if the problem persists try increasing the Calcium fertilization by about 30-50%. Btw the top leaves curling and folding upwards are clear signs of light/radiation stress, you might want to increase distance from lamp to plant by about 5cm to stop it from getting worse. Hope this helps! Good luck and happy growing :)