Product review (3 stars): gets moldy fast, but does the job
This filter is factory standard, and I've purchased a dozen or so in the past two years.  I've found that soaking the filter in a mix of 1/50 bleach and water monthly will kill the mold and saves me $50 an year on the ProTec cartridges.

You should rinse out the filter afterwards, but do not squeeze the filter.  It gives the filter about 3 to 4 months of lifetime before it starts to come apart.