I'm not an expert, but I do have 7 PCF's that I've been raising from newly hatched tadpoles and I haven't lost any yet. The only things I did different were I had a rock in the water that they really seemed to like to climb onto when they were morphing, and I never put a light on their tank. I just had it at room temperature.

Anyway, those are a couple of ideas. I hope you are able to figure it out.