@SkunkleDamo,
before flowering, I changed 100% the solution once a week. for flowering, when it took 5 liters per day, I changed 100% of the bloom every three days, because the ph began to jump. it was on mineral fertilizers powder feeding. On simplex organomineral fertilizers, there is no such problem. although by day 10 it became worse to assimilate the solution (the ppm level up), but after replacing 2/3 everything got better again