Apparatus is provided featuring a signal processor or processing module configured at least to: receive signaling containing information about the conductivity of a fluid contained, processed or flowing in a pipe, tank, cell or vessel having electrodes around the circumference of the pipe, tank, cell or vessel in an irregular configuration; and determine a scale build-up in the pipe, tank, cell or vessel using a tomographic processing technique, based at least partly on the signaling received. The signal processor module may be configured to provide corresponding signaling containing information about the scale build-up in the pipe, tank, cell or vessel using the tomographic processing technique, e.g., including where the corresponding signaling contains information about a chemical to be injected to control the scale build-up, including in a closed loop manner.