How do you control integrating processes like level in a tank?

Integrating processes have no natural equilibrium - output continues changing with any non-zero input (level rises/falls indefinitely). Control characteristics: process gain is ramp rate per unit input, no self-regulation. Tuning approach: integrating processes require tight P-only or PI control; derivative generally not helpful. For level control: determine required tightness based on downstream needs (tight control for feed to sensitive process, loose control for surge tanks). Accumulator sizing affects control difficulty. Lambda tuning for integrators: Kc = 2T/(K*lambda^2), Ti = 2*lambda.