Aldrovanda vesiculosa is not supposed to like hard water. Utricularia
spp. are supposed to take a little Ca, but not like really hard water.
I have only grown Aldrovanda in very soft water (10-30 ppm KH, 0 GH) and
Utricularia in water with very little Ca. Next year I may try an
experiment with giving them more Ca. As long as all other conditions
are ideal I expect that both Aldrovanda and Utricularia will be able to
handle a little more Ca.
As for typical aquatic plants I have found that those native to soft
water can grow in the "liquid rock" that come out of my tap. Although,
they may well show an initial setback due to the initial change in
conditions.
Later,
Bill
I've grow both genera in very hardwater, not a problem.
CO2, good NO3 etc.
The CP people love it when I send them some.
The terrestrial species are not so similar though in their needs.
Regards,
Tom Barr