Barney's G13 Haze

Day 1: Watered with 3 L water with nutrients, pH 6.3. The plants look well and are thriving. Day 3: The two new main branches on each plant were topped after the first node. Day 4: I noticed that the large bottom fan leaves had brown spots on them. The leaves were cut off and examined and after some internet search, I concluded that the brown spots were probably due to a pH burn. My pH has probably been a bit too low in the waterings, so this time I adjusted the pH to be a bit higher (between 6.5 and 7). The plants were watered with without nutrients. Day 5: The plants were checked for additional browning of the leaves, but there was no browning. The lamp was lowered to 20 cm.