15-30-15 ok for flowering???

Was wondering what npk ratio to use for flowering?? Is 15-30-15 ok???

Yes; but there are 3 stages of flower stage:
early flower use nutrient high in "P" than "K" (your 15-30-15)- weeks 1-2 of flower
middle flower use nutrient high in "K" than "P" - weeks 2-4 of flower
late flower use nutrient high in "P" than "K" ( your 15-30-15) weeks 4-6 of flower

It will work but consider getting a bloom booster with higher K amounts than P amounts for "middle" flower