With the
drip system you can water continuous for large plants if you use
grow rocks. If you don't then read reply below. Yes you recycle the same water and when you need to add more water mix a gallon at a time with the correct amount of
nutrient mix if you don't have a ppm meter. (About one tablespoon per gallon of water for most mixes.) That way you can keep track of how much you are adding.