Originally Posted by holoublahee
What does EI mean?
EI stands for Estimative Index.
It is a dosing regimen.
Giving your lighting (and assuming they are T5HO bulbs), you probably have enough plants and light to benefit from EI dosing.
For your CO2, are you using a drop checker (with a 4 dkH reference solution) to ensure that you are attaining levels around 30 ppm?