Now you just said the opposite of what intuition suggests without any evidence, or even argument. Please elaborate and don't just heat up the discussion!
Black is the best colour to absorb UV. You want the UV to not reach the water, so you want whatever is on top of the water to not allow UV past.
UV + Chlorine = Bromide
Does that look like an explanation to you? I don't see anything about black. I don't see anything about white. I don't see anything about reflecting materials. I see something from chemistry, maybe?
Customer: "Why should I buy the product?" Developer: "Here we had a problem with the inheritance tree. We worked around it with a factory method."