Yeah, installing an in-line filtration unit is a smart investment because they always pay for themselves in short order. Keller (http://www.kellerproducts.net/inline_filter.htm) is what I'm most familiar with but there are other makers out there as well.
The foaming issue is most likely from the water being too soft (hardness<70ppm). Could be from overly rich concentrations too. What do you typically mix to and how are you verifying that? Refractometer??