Need A 2nd Opinion

Lately my plants have been turning yellow. Im pretty sure its due to a nitrogen def. I just want a second opinion on this.

Also what can I do to help this deficiency. Ive heard a small bit of urine can help. Any truth to this ( i know sounds a bit nuts)

Heres some pics

i dont recommend pee lol, just get some high nitrogen nutes and it will pull out of it on itself. get some general hydroponics flora, there is 3 liquids that u mix together to make your own concentration, so u can control how much of what u give it. check it out, its about 40 bucks for 3, 1 liter bottles. its what i use, for soil.