Indeed tony, as i said before i think in DWC you could run the first RES on Root stim like Rhizotonic alone its NPK 0,6 - 0,2 - 0,6 i would say thats ok to start an auto seedling for 4 or 5 days.
Mine are at 5 days now and the EC is 1.0 of canna plant start on some buckets and formulex on others, that may sound a lot but the starter nutes are low NPK .My water is 0.6 EC without nutes so my plants are really running 0.4 EC. I doubt very much that 0.6 EC in my water has much that the plants use, mainly its calcium and lime i think.. plants use cal but im not sure the suff in the water is in a form they can .