I just read this thread start to finish and I know exactly what happened. My brother, you need to keep your water temps BELOW 65 degrees in a brand new system until the microbial population has a chance to sort itself out. 68-70 degrees is just too high until you have a solid colony of beneficial microbes.
Fire up round two, get your temps down, clean out the gunk in your system and flush a few times- and as counter intuitive as it may sound right now, STOP USING STERILANTS. Unless of course you'd like to be totally dependent on them until you've grown a pathogen so strong that it takes killing your own plants to get rid of it.
I have been down both branches of this road, my friend. You can spend months/years figuring it out on your own, or take my advice and be running hard with a bumper crop next run. Your call.