Hey Tom! How are those plants coming that you bought from me?
I was dealing with the same issue you are having and I went and bought a RO/DI unit. Here is a link that you can read and see what you think.
http://www.plantedtank.net/forums/wa...lants-not.html
I thought about the idea of using peat but found to many bad experiences with it. As far as I know, those are the only 2 options (peat or RO water).