I just read the stats you posted on your tap water and I have harder water with a pH of 7.8 from my tap. My fish do fine in my water although I would be a bit suspicious if the tap you are measuring has already been through a water softener, that thing that uses salt, before you measured it. If it has, your natural water is far too hard to use and will have far too many minerals in it after substituting sodium for most of the calcium and magnesium in he water and still measuring over 200 ppm GH. You should probably try to measure some of the water before it is processed or as an alternative measure it with a TDS meter. The spring water is a great idea for diluting the tap water but at only about 1 degree of hardness is too lacking in minerals for all but the most soft water tolerant of fish. What you are seeing is water in those springs that is comparable in purity to the water they are trying to sell you at your fish shop.
Slightly confused.. in short I should use the spring waters from the mountains here because its measuring the same as the tap water.. but hasnt been treated (for worse then better again in this case)
Correct?