Water Based Excecise Machine

People always seem to complain that the motions of a weight exercise machine made compact is not as "smooth" as a giant tower with actual weights that move up and down. Several ingenius designs such as the Bowflex have already been devised for this problem, and I think I may have another.
Center the whole machine around a giant tube of a high viscosity liquid like one would center a traditional machine around a tower of weights. The resistance is generated by trying to move a porous plate up and down the fluid filled tube by pulleys at the top and bottom of the tube which attach to the plate through the liquid. The first plate would have very big holes in it, giving little resistance, the second would have smaller holes and so on. Without the 300 pounds of iron bars to lug around and using water as the fluid, this device could be emptied and carried around quite easily and provide very literally "fluid" motions and feel to the user.