So far, so good. I've performed a nutrient addback last week, and I'm due to perform another tomorrow. My plants look happy and healthy, and are growing at a terrifying rate! I've noticed that over the last few days, my PH has slowly began to drift downwards. I've added a total of 4ml PH up so far in the last week and a bit, which isn't much at all, but before experimenting with addbacks my PH would barely move. My roots look and smell fine, so I'm doubting its root rot or anything like that causing the PH shift... Possibly just the nute balances shifting as the tank gets older?