AN = advanced nutritions. I have a 600w and a 400W HPS One on top and the other from the side for light. As far a watering goes I'm using a DWC setup and only add water. I add about 2 gallons of water a day right now plus nutes. I have 9 plants in a 10 gallon rubber maid tub. They will stay in this the whole flowering. I never flush the system until the end. Never had a problem. Most people flush every two weeks but I think its a waste. 6 of the plans are master kush and the other 3 are Ak.