What deficiency is this?

How can anyone tell me what's happening with my lower leaves?

Did you dump nute water on em when you fed?

A little by accident the nute water would do that?

Yep! it's just 'splash-back' any time you get water or nutes on the leaves- especially if the lights are on, it'll get burned.

Best option is to trim out the bottom so the planter is more access able and none of the leaves will get soaked when you feed or touch the soil.

it sort of looks like too much nitrogen as well. the leafs are a really dark green. maybe not, but it looks a little dark to me.

Looks like your still in veg so no worries. Clip off those low leaves.