I use Jack's pro 15-5-15 +Cal-Mag.
Like the MSU fert, this fert is formulated for low alkalinity water.
But my tap water has medium alkalinity. So I adjust my diluted fert
solution pH to around 5.5 with citric acid. This decreases the
solution alkalinity to the right level for that fert (from 60 ppm
alkalinity to 10 ppm).

If you have the june edition of Orchids, there is an article on the
MSU fert. They used the MSU well water formulation with very hard tap
water, but they also adjusted the water pH with an organic acid to
decrease the water alkalinity (and pH).

Hope this could help.
Laurence