What is the optimal true watt power for veg, bloom...

Hey man if it’s the non dimable 450w Viparspectra I’m using the same. It’s had some bad press but overall I think it’s good for what I need it for which is a cool veg light. As Chilium said use both switches veg&bloom together for the entire grow. Your seedlings look waterlogged. That is from overwatering. At this stage I would advise you do wait till the soil in your pots has dried out almost completely keeping an eye on the plant for any sign of droopy leaves after the top layer is visibly dry (check every few hours) then add more soil till it reaches the rim of the cup. This will aid the stability of the stem. Then add some well oxygenated plain PH stable water 6.5 is perfect for soil. Good luck