Steve, thanks for the suggestion. Been using White Shark 1x/week at recommended strength. Apply it with the weekly PH water only "flush"....instead of adding it directly to the nutrients as scheduled. Boosted the nutrients too and in combination they seem to be helping quite a bit. Seems like you have to be more diligent with the application of nutrients and beneficial microbes when working with a coco/perlite mix than with soil or a combination of the two.