Black Bloon is essentially a +30 HP White Bloon that delays the card draw, or a -10 HP Yellow Bloon that costs 2 more, but also draws a card.
Black Bloons cannot be one-shot by Storm Of Arrows unless already damaged by another source.
If your hand has 6 or fewer cards after ending turn with a friendly Black Bloon about to leak, you can assure that the extra card draw will not be wasted.