How often should i change the solution. and is it ok when you flush the solution out to let the roots be for a minute or 2 while i pour the new solution in?
If you know your beginning amount you can change it when you have added as much as you started with. 3 gallons to start=flush when you have added 3 gallons to top it off. Two weeks is another good rule. Some feeding schedules are on 2 week cycles so you can flush and start with the new recipe each time. The roots will be just fine for a while. I just change the res without an actual flush of the grow medium or roots unless I am changing from grow to bloom nutes. I havent had to do an emergency flush to fix anything... yet. Still on my first grow but finishing soon.