A few observations:1. Placing directly onto the heating pad may make the medium too hot. Does the heat mat have a temperature gauge that you can adjust? I have one that doesn't have a gauge so I place 3-4 layer of towel between the heat mat and cups.2. Clear cups expose the roots to light and roots don't like light. They are however great to see root development. Are you able to simply slide those cups into non-clear cups? That way light doesn't hit the roots and you still have the benefit of being able to see the roots through the clear cup via sliding out of the other cup. Does that make sense?3. Just curious to know why you only filled the cups half way with medium.
4. Are there holes in the bottom of the cups for drainage? If so, how many?
A few observations: 1. Placing directly onto the heating pad may make the medium too hot. Does the heat mat have a temperature gauge that you can adjust? I have one that doesn't have a gauge so I place 3-4 layer of towel between the heat mat and cups. 2. Clear cups expose the roots to light and roots don't like light. They are however great to see root development. Are you able to simply slide those cups into non-clear cups? That way light doesn't hit the roots and you still have the benefit of being able to see the roots through the clear cup via sliding out of the other cup. Does that make sense? 3. Just curious to know why you only filled the cups half way with medium.
4. Are there holes in the bottom of the cups for drainage? If so, how many?