How do i use kelp powder?

I have been reading about kelp, apparently it does some pretty amazing stuff for your plant. I picked up some Burrpee - All natural plant food, made from water soluble kelp powder. it has an NPK ratio of 0-15-11. So no Nitrogen. So im guessing that i need to use it with another plant food, so i also have another plant food called garden club select plant food, organic all-purpose. It also says OMRI Listed. Its NPK is 10-2-8. So my question is should i use them together during veg. or should i use it when i get to flowering and use it with my flowering plant food, or both. or even neither?

here is a pic of the stuff.
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Some one.... annnyyy one... please help.

its a bloom booster it fattens up your buds in the last weeks of flowering, you add it to your flowering nutes