Manually dip the rw cubes in your water , let them drain a bit, and set them on top of a warm reflector.I think mine is around 82f. Dip them twice a day.
I'm using aquaponic water with nutes at1000ppm. And seedlings are thriving.
In nature, few seeds drop into 0ec/ppm , pure, sterile water.they usually fall into soil with nutrients and microbes. I can't say for sure, but i think the aquaponic water takes credit, because I've tried many other methods and i suck at germinating seeds.
Try aquarium water if you have one, justbe sure to ph it first. I'm a assuming that the nitrogen is in a more natural form. I also have all kinds of naturally occurring nitro bacteria in the water with endomyco spores that i added.no cloning gels or hormones added but a little superthrive added a few days before germ.