DIY 5 gallon Slow sand filter update for February 2014

It is now February 7, 2014. At this location its been below freezing at night for all of February, and for the past 4 days not above freezing at all. On the 6th of Feb. at about 4:00 am, the low here was 13.5 degrees F (-10 deg C).  All of the filters are frozen solid with the exception of the larger filters 2 and 3. They are being fed with water from the shallow well that is heated by the un-frozen ground here and the pump house has a very small heater to keep the pump from freezing; the water must run continuously or it will freeze in a few minutes at 14 degrees F.  All of the ponds are frozen. It will likely be at least another week before we can continue running water through the filters, and then at least another 3 weeks until we can do another test.  Probably the first part of March at the earliest, weather permitting.