[villagetinker]

You should be able to take the filters to Lowe's or Home Depot to get replacements, if you are not sure which filter should be first, I would do an internet search. Also, your system should have a bypass, so the procedure is to open the bypass valve, close the inlet and outlet valves on the filters, and relieve the pressure on the filter housing (usually a red button on the top of the filter housing), then you can remove the filter housing and the filter cartridge.