Yeah HC,UG,DHG are a pain sometimes with growth. DSM (Dry Start Method) is a great way to get things kicked in over-drive as long as you don't get spider mites or mold.
Tips: Putting foreground plants into individual bins to propagate is a great way to start things. Some plants have less demands compared to others (UG likes being a bit more marshy where HC is the opposite)
You can remove variables by using RO water then PPS Dosing that water so your plants get the most nutrients out of water column.