I'm no expert in this area, so take what I say with a grain of salt.
What is it you expect to "purge" exactly. The i30 has of course a diesel filter that if replaced at the correct intervals, will protect your car adequately.
Water in diesel is not a common problem, but still possible. The fuel filter has a water float built in and if water collects, the float will light a warning on your dash. If this happens do not ignore it as water will eventually enter the motor and can destroy it.
The modern Common Rail Diesel, which ours are, operate at significantly higher pressures than older diesel motors and generally, any additives to fuel, tend to reduce lubrication at the diesel pump and injectors which could have bad consequences over time.