Matt, good information. Turbulence is extremely important, equally important is the volume of chems in the tank. Many people mistakenly over fill the tanks thinking they will eliminate any possibility of surge marks or undeveloped edges. You need a certain amount of air in the tank to facilitate proper turbulence and even development. Also, with plastic tanks, many times I've seen where people leave out the center core lock that prevents the reels from climbing the core, resulting an underdeveloped edge, which then makes them over fill their tanks.