ive given up with soil growing and i give up asking for advice in the basic growing section as there seems little support so im going to try hydroponics this time around, just hope there is some support in this section.

i have setup a small drip system ready to grow 4 plants but what i dont understand if the feeding methods. how long does the nutes last in the water and how often should i change the water in the resovior? the ionics bottle says to feed them x amount per 1litre and then feed the plant once every 3 - 4 days but do i just feed them only water inbetween those days? ive had nothing but bad luck with my last 2 crops so some good support would be much appreciated. thanks