I don't think sunflowers are as allelopathic as people think.

greendot ... You need to track what you are doing and track the results, then decide or give us the data to analyse.

Because right now you have "some trays of peas germinating well and some not so well" and you have not even told us how many trays are in which group and what medium they are in.

lazygardens,
You say I need to run a trial and give you the data to analyze. I have the statistical skills to analyze data myself and am not asking for data analysis, and am certainly not at the point of spending time running trials. I asked what others experiences were with media reuse, as I had a vague suspicion about possible allelopathy.
I am rather new here. Is asking for others experiences inappropriate? I hope to share my experiences also.
Kind of felt like I asked for others experiences and your answer was to figure it out myself. Am I wrong or have I greatly misunderstood thinkgs?

little_minnie, thanks for your reply.