That's a big pot to be watering every 48 hrs at this stage I had mine in 5 gallon pots and when they were this small sometimes watering every week was too much. When there is too much water present in the soil the plant can stop growing roots and this will lead up to it not taking anything in. When I start my autos I put some coco towards the center and plant in that so it drains really well and I don't throw alot at them with the nutes in the soil.
Growing GSC auto in a 28"x28"x63" Spider Farmer Tent , SF1000 led,Heater between 73 and 79 degrees F. , 1 small fan , Inline duct fan with charcoal filter for exhaust, humidifier running between 55 and 60 RH depending on watering plant. Grow medium is Roots Organic Original . 5 gal Fab pots, Roots Organic Terps Tea (bloom and grow) , Blackstrap Molasses . I stretched her in the beginning , 1st time with leds. I left room in the pot to add more soil in case of this happening . Added soil , lowered and intensified the light. So here is a photographic view of GSC auto's journey!