What’s up! I grow rdwc myself. What you want to do with dwc is called “reading the res.” You basically take a sample and test ppm. If the ppm is higher than your initial input then you add water. If the ppm is lower than your initial input then you add more nutrients. It’s basically a numbers game. You want to decide what ppm you need to run based on plant size and where it’s at in the growth cycle. This is a huge variance between people and mainly depends on your environment and how comfortable you are with growing. With dwc less is more generally. Seedling 200-250ppm, early veg 400-600ppm, late veg 800, and 1000-1200ppm in flower is what I aim for personally, but I push my plants hard usually.

Inflow and runoff are for drain to waste. Dwc is constant submersion. There is no runoff. It’s essentially all inflow.

Without running a recirculating system, remember to change your res ever 10-14 days. Nutrient imbalances will occur and you’ll end up with tip burn or worse. Don’t worry, it’s easy once you get the hang of it.

One more thing. Know what ppm scale you are using. There are 3. Or skip all the shenanigans and switch to ec if you want.