Week 5 Flower Brown Leaves

Your feeding ratio is wrong. Flowering npk is 1-2-3. Cal mag is probably a good product to use as well. Would also check ph.

Check your diary. You're watering with a pH of 6. Raise your pH a few points between 6.2 and 6.5. This way, calcium, magnesium, and potassium will be more available. I read that your lamp is at 35 cm; if it's at maximum power, you might want to lower the intensity a bit or raise the height to 45 cm. I think this observation can help. Cheers.

A combination of nitrogen toxicity and cal/mag deficiency.

Looks like a calcium deficiency to me. Your best bet is to increase your dose of Cal/Mag immediately. You can also go to your garden center and get a calcium foiler spray which will provide immediate absorption for your plant. I generally do not like to do this when flowering but you can easily hit just fan leaves. Spray at night when lights are off. When you water next, over water by about 20% and test your run off. If off, correct your mix accordingly to bring it back into normal ranges. Hope this helps.

your ph could come down a bit to around 5.8 this would be better for optimal nutrient availability as for deficiencies I can see a slight calcium problem so yes a calmag additive would be a good idea mate