While it is true that conventional mechanical filters can remove particles in the same size range as magnetic filters, the majority of these filters are disposable and incur a cost for each gram of particles removed.
There are other penalties for using conventional filtration, including energy/power consumption due to flow restriction caused by the fine pore-size filter media. As pores become plugged with particles, the restriction increases proportionally, causing the power needed to filter the diesel to escalate.
VTR Magnetic fuel conditioners:
The VTR magnetic fuel conditioner is installed between the fuel container and the primary filter. The fuel is filtered, the fuel particles are broken down and the smaller dirt particles will be held by the filter which will take longer time to be blocked and need replacing and the fuel burns more efficiently. At the same time you have clearer exhaust fumes.
The present of water in the diesel makes it easier for bacteria and algae to build.
This is where you need to filter the diesel in your tanks occasionally to remove the collected water and what ever dirt or bacteria that have been collected.