Product review (5 stars): Your Pinguino Water-To-Air Cooler Needs A Functional Limescale Filter
This filter is deployed in newer (about 2008-up) Pinguino Air-To-Water-To-Air Portable Air Conditioners.  It's a quantum leap upwards from the old way of building these air units, in which water from the sink source spilled directly upon the cooling coils, thereby leaving system-clogging calcium-mineral deposits all over the interior of the water cooling transport system.  Yuck!  The tiny chemical balls inside the filter are similar to the ones employed in USA-Culligan water purification shower heads, which suck out chlorine and other contaminants from water that passes through it.  In this DeLonghi example, the results should be even better, because the water cycles very slowly through the filter media, for very thorough contact.  If you own a water type Pinguino Air Conditioner, you need to keep a spare one of these filters handy, especially if you use hard water in your air conditioner.  The expected life averages three to five years if using straight sink water.  If water is prefiltered by Culligan or Pur, for example, you'll get more life from your filter.  The price for the filter on Amazon is excellent, about half what you'd pay from a HVAC repair parts house.