I am aware that crypts do not like change, and it is very common - almost certain - that they'll melt shortly after being planted in a tank.
I decided to experiment with plants rooted in the substrate, and everything I've read says crypts are easy beginner plants. So I bought one on 20 October 2020. This seemed to do well, lots of new leaves, while the old ones slowly disappeared. So I got 4 on 23 November 2020. These all did the same - new leaves and the old ones slowly disappearing. Finally 3 more on 7 February 2021. All the different species were chosen because they didn't need strong light. All were doing well. Until 8 March.
I did a water change on 6 March after which the leaves on every crypt started to dissolve - no matter when I got them, they started to disappear.
One of the most recent batch has 1 leaf left; another is just a single stalk about half an inch long. The others do have a few leaves each but nothing like what they were before the water change.
Is it normal for this to happen? All the crypts, whether planted 1 month ago or 4 1/2 months ago, melted at the same time.
Or is it something I did at the water change?
I should add that all fish and snails are accounted for and the unknown number of shrimps are as active as ever. So it's not a contaminant.
On a totally different subject, I received an anubias and a java fern this morning from an Ebay seller who sells shrimp safe plants. Both labels were marked with a UK plant passport.