Currently there is zero reason besides aesthetics to build more than the minimum fracking tower size using 1 tower section. But it has a max of 5 tower sections.
How about making it so each tower section after the first makes the fracking process more efficient by reducing the fluid used by 12.5%? Especially since each tower section adds to the power consumption.
Having 2 tower section would reduce fluid usage by 12.5%
3 would reduce it by 25%
4 would reduce it by 37.5%
And having the max of 5 tower sections would mean the fracking process uses 50% of the default fluid.