Hi all,
The addition of calcium and magnesium will raise the dGH, although that addition will make little difference to the hardness of our tap water, as it is about 16dGH all ready. With the carbonate hardness dKH and alkalinity, it depends upon the compounds used, hydroxides will raise pH, and carbonates will raise carbonate hardness, but as a general rule sulphates, phosphates, nitrates and chlorides won't raise either. The ions from the EI will raise the conductivity, but in our tap water that is all ready in the 650 - 800 microS range (from the dissolved calcium carbonate).
Personally I wouldn't keep any soft water fish in high conductivity, or strongly carbonate buffered water, but many of the other posters on this forum do, and don't worry about it.
cheers Darrel