Blades, I have decided to embark upon a new adventure. Growing RDWC instead of using soil or coco. The reasons are many. First and formost, I hate coco! (and soil!). , The two primary reasons are I hate hauling it in and hauling it out. I live in the city, and I dont want my neighboors or anyone else to be aware of my legal grow (for security reasons). Hauling it in and out in the middle of the night is seriously bad news. Disposing of used dirt and soil in the city is also a problem, a lot of my fellow city growers resolve this by dumping their used soil on the city streets ( I see soil dumps everywhere in my neighboorhood), and hauling it to the dumps is a problem, logisticly and for security reasons..Harvest weight is another reason I hate the stuff. I grew better pot and harvested more using bubble buckets made out of 2lb plastic coffee cans than what I was doing in 5 gallons of soil or coco. Plus using soil or coco, I noticed a higher amount of dust flying around the grow room and the house in general. So I rigged up some 5 gallon bubble buckets, and the quality and quanity of my harvest improved on the very next grow. Not were I want it but improved. Granted I could have worked the bubble buckets for a few more grows and fine tuned that. But its still not going to be the kind of harvest Im looking for.. So on a trip to one of many local hydro stores, I ran across a palet of used Counter Culture equipment. After some haggling I got him to drop his price by $200, and walked out with 50+8g buckets, multiple epicenters, magdrive pumps, commericial air pumps, uniseals, pvc, manifolds, even a nice 1/2horse chiller. Since my grow environment consists of multiple grow and veg rooms, I will be building several systems with the counter culture equipment. Each with different numbers of pods or buckets.. So my first question is does anyone know the proper formula to use to determine the correct size magdrive pump for a particular configuration? Im not really looking for an answer like ' I use X magdrive pump for YY buckets configuration and it works great...' Im really looking for the math here. Using the math, helps to reduce potential problems, such as determining how a certain size chiller will perform, etc....and save me money by knowing instead of guessing..Im an engineer (networks) so I know the keys on a calculator, but I never studied fluids in college (other than the effect of large quanitys of it (beer, specificly) on co-eds!) The first configuration Im working on at the moment for one of the bloom rooms. A 16 (8Gallon) bucket configuration with dual 8G Epicenters and a 30G water top off tank. Plants will be under 4 600w water cooled lights . Pictures coming soon