NL Auto

think of it this way... you provide nutrients at the correct concentration. you feed it as it drinks -- especially a mature plant. if you see a slow buidlup or slight sign of darkness that isn't normal or related to senescence, i typicaly switch to every other for 1 or 2 cycles of each and by that time it's cleared up. you basically have to combat evaporation with a plant in bloom, and in many contexts even that may not cause a problem in the time it takes to harvest a plant. plenty of people don't flush in coco... some need to because they feed more heavily -- likely throwing money down the drain too. I rely on color of leaves, but maybe 1/4 gallon every 2 weeks that late in bloom? could just spread it out a bit too... and if that small amount, likely can power through to harvest in many cases - not suggesting that you ignore some darkness, but that it may not even display in that amount of time. if you want to be more precise, you'll need some meters and take some notes until you have a good baseline of min/max and what causes problems... you'll know proactively to give a little water sans nutrients. I really like the option, but not going to callibrate and maintain that crap, lol. i'm nerdy enough otherwise.