I have 4 indica strains in a Wilma system. They are 21 days old. Thay are in 2" rockwool cubes, and the cube is in clay pebbles in 3 gallon smartpot. I have a chiller and the solution temperature is always 19-20 Celsius degree. The tent temperature is 26 Celsius degree with 65-70% RH. I have tap water which EC is 0.5 (after 50-50 tap-RO). I have horticulture nutritient named Ferticare (like Jacks pofessional) 6-14-30. I supplement it with Calcium Nitrate. The solution EC is 1.4-1.5. NPKCaMgS roughly: 110-36-150-120-40-30. I know my water is bad, so i sent a sample to the laboratory. I am waiting for the result. I have home made drip ring. The feeding pump is a 2500 liter/hour pump and it is working 24/7. I use phosporic acid as PH Down and i must use a lot due to alkalinity... EC is stable for days. PH 5.8-6.1.
The rockwool cube is 5-8 cm below the top.
I have 250W 4200K CMH lightning.
The plants are fade green with some yellowing. It is browning from the bottom.
What is the problem with my ladies? It is the water? Or is it overwatering? Or something else?