Quote Originally Posted by demoreal
ro water is not unstable, there is nothing in it. Taking the pH makes no sense.
when you add nutes you may need to let it settle for a day.
RO water is pretty unstable. RO water is almost electrically neutral, and as such it will grab most anything it possibly can, from oxygen and hydrogen ions down to most anything else (RO water is one of the best solvents in the world due to this property.) This causes mad changes in pH, very rapidly. After making RO water it's best to let it sit exposed to open air for a day to allow it to come to ionic equilibrium.