How do you know when the nutrients are out?

first time grower and just received my grobo…love it but have a question about when to replace the nutrients…I don’t see a setting in the UI or app that will alert me when the nutrients are low so figured i would ask the community for guidance…


You will have to manually observe the bottles. Once the contents level becomes lower than the point of which you think will be used during your next water change, pull the old bottle, replace with new bottle, run your drain/fill, then pour in the remainder of the old bottle into the new.