Here in the American West and specifically, where I am , on the banks of the Yellowstone River , snowmelt from the mountains is what gives us most of our water . Right now the snowmelt has peaked and will gradually dribble down until fall and then in winter the river will run low . Two weeks ago the water coming out of the tap was 48 PPM TDS and today it’s up to 73 PPM TDS . That’s soft water no matter how you slice it or dice it . Doing my water changes with that water suits most of my fish and even my Endler’s ( Guppies ) and Platy’s are okay with it but guess what ? The duckweed in my livebearer aquarium is , for all practical purposes , GONE ! Did this soft water kill it ? My hornwort in the same aquarium has slowed its growth dramatically . It isn’t dead but it’s holding its own . I used to thin it a lot every week and lately I haven’t . What gives ?