What is your light?
Are you dosing ferts?
Looks like you have mostly stem plants. They love KNO3 (potassium nitrate) and need a carbon replacement.
KNO3 sources are:
Spectricide stump remover is 100% KNO3 at Lowe's in some States
which needs to be diluted
30 ml (3 tsp or 1 Tbs) into 1 cup of water. 1ml = 1.08 ppm of NO3 in 10 gallons of water.
Carbon replacements are:
API carbon booster
Metricide or Cidex
or Cidex is 60% stronger per mL. For Excel (1.5% Glut.) versus Metricide (2.5% Glut) Mathically is 1.5/2.5=0.6. is Thus dilluting 6:1. A quart is approx $25 on no ebay links allowed Best to use a mask when diluting in well ventilated area for can be hazardous to respiratory system. I have pleurisy but use it.