Update: April 28 2025:
It is now 2025. The filters we started in 2007 are still here. Filter one is still functional and working. Another at the other side of the house is also functioning and supplies water to farm animals here. The other filters need some work. The newest filter here is filtering water for a fish pond. There are 7 fish in the pond and the filter has been active for 6 years now. Absolutely clear water in the pond, no odor and the fish are just fine and growing. More info will be forthcoming as well as a video. Also we plan on doing tests on the oldest filter , Filter 1, after having not changed the sand since 2008.