Definitely nute burn. Its on the tips of all of the leaves. Must be some powerful soil. Week 9 of flower? Have you started your flush yet? If not, I would. They will really start to turn brown as they use up the nutes. Good growing.
Lights - Mars Hydro TSW - 2000W. X2
Germination started 5/9/21.
5/16/21 All 6 are looking good. Waiting for roots to show.
5/17 - Reservoir - PH 6.1, Temp. 69 degrees, PPM - 418-423
Running Rapid Start, General Hydroponics Nutrients. Dosage 1/4 tsp. Per gal.
Did first water change and added GH Nutes to the mix. Water temps are running 75 degrees but all roots are good and white. PH is running 5.6 to 5.9 average. PPM 430 - 435.
Started 2 Skunk 1's that ill be running in the 3x3 tent under a MH SP-150. Think ill need more light? I will be posting this grow under another header when they start to grow more.