Don't change anything! No matter what your water / fertilizer / filtration / flow / substrate is like the crypts are going to shed their leaves and they will grow new leaves more suited to your tank conditions. Changing stuff around to try to save the leaves the crypts come with is just going to throw everything else in the tank off. Give it a month and they will almost assuredly have grown new leaves and be happy. Any monkeying with the tank parameters is just going to extend the time it takes for them to get comfortable in their new home.