16 pot system with sprayers in each all hooked to the main rez ?

Is it gavity feed back to the rez ?

It sounds very much like pythium (root rot) from the rockwool staying too wet for too long. Dark green fungus on the rockwool.

How do the pots fill up when sprayers are on ? How long does it takes them to drain back ?

Would very much like to see some pic's. I bet your problem will be solved when we see it. Many here to help and a pic says just about all. some systems need to be tweaked about watering. Once you tune it in it will blast.