C keei and c affinis proves to be very prolific in my 90g hard water tank. I had both plants for over two years and I get one or two runners emerging from the substrate from each mother plant a month.
Here are some general growing info:
They're grown in tap water from Glendora. TDS meter shows that they are on the harder side with 330-340 ppm. I have two eheim classic 2217 and 2 mesh modded octopus 1000 needlewheel for CO2 and current on both ends of the tank.
I use earthworm casting with a red clay mix as the main substrate. The worm poop is capped with very used aquasoil.
I do not dose nutrient into the water column but I do have a school of cardinal tetras that are fed every other day.
Every square inch in the 90g has movement and saturated co2. Movement and CO2 distribution can be read by looking at the flow of the tiny CO2 bubbles suspended in the water column. You can see this in the two photos below.
In my experience, the key in keeping these crypts happy are stable parameters, good current, continuous supply of nutrients, and ample co2. Lighting is not so important, given that its sufficient.
C keei is a hard water crypt but I also have them grown in my 55g soft water CRS tank. There is no difference in growth pattern. However, emergent growth is a different animal. I cant seem to keep it alive...
I have c sp bukit ibam and c uenoi grown in this tank as well. They're alive and growing but not at the same pace as keei and affinis. These are doing much better in a soft water tank. I'll post some info on them later.