Ok I think what you are asking is if you refill the reservoir with nutrients when the level drops? Is that close?

You do a full nutrient change every 7-10 day's. It's safe if you use just Ph water on day 11 then on day 12 go back to nutrients. That will keep you from having lock up problems but it does use more water. If you can't do a quick flush after each water change that's ok you don't need to but it's a good idea if you have the water.

Now your EC or PPM will change after you put it into the reservoir and the plants use up some nutrients and deposits more back into the res. So the reading you take on day one is only good for day one. There should not be a change of more then a few hundred PPM points from any 24-hour period. Make a plot chart and track your PPM/EC you will see the pattern.

If the level drops and you need more water in-between changes then just use PH adjusted RO water to bring it back up to the normal line.


Does that answer your question?