I am letting my deep water pump run 24/7 and am in fact running a dual pump with 2 air stones. These have been running for 24 days of growth and I am now in the 22nd day of flowering. Running the pump 24/7 I am adding water with fertilizer every other day because the water level drops. Every 4-5 days I pour pure water into the root pots . I have have not done a complete flush and the plants are doing very nice. I am using fox farm nutes and a four gallon dwc. Not a expert by far but this is working great for me. The lights just turned on so the fans are drooping a little bit.