How to I determine whether I need a small whole house water filter like I saw installed on the TOH video or a big steel one that costs @$4,000. I have one in my garden shed and was told by the previous owner I needed to put limestone in it periodically. I can't find where to do that on the tank, the hardware store had no idea what I was talking about and the model of tank is out of business I believe (Uniflex Components Inc / F00079691044F / Model UF-1-AN). My water source is well water and my tub water looks very rusty. I am also afraid the copper pipes are being affected. Thanks for your help