you need to balance you timer's setting with the output flow of your pump, i dont know how many tubes your planning on floodin, but if you pump is not big enough, you wont be flooding all of them with the same ammount of water. 1 min on may not be enough water with to small of a pump. if you are using a 15 min on pump, wich i use on drip rings in DWC i run it 3 times during the day cycle, with no signs of overwatering, i could probably bump it up to 4 times during the 12 hr. its basically a trial and error deal, just expermient with it before you get the plants rockin. good luck with it, i brainstormed the exact same setup, before i decided on 5 gal bucket/tub DWC.