Plants under LED grow lights need less water than under HID lights like HPS or MH. Cut watering to roughly half of your HID routine — if you'd normally water 6 times a day in a given system and medium, drop to 3 under LED. Less heat means less evaporation and slower uptake.
Over-watering under LED is one of the most common mistakes growers make when switching from HPS. Watch the medium, not the calendar: let it approach dry-back before the next feed, and your roots will thank you with faster, healthier growth.