What color is the water itself supposed to be when you have Mustard Algae? I have green water but when it settles to the floor it puffs up easily into a yellowish cloud but I have green water and can't see the drain 10 feet down. So, what color is the water supposed to be if you have mustard algae? I've had green before and know that the water is green and can be almost black if it is bad. I've been told by a neighbor that what I have now could still be green algae and have the same characteristics of puffing up into a yellow cloud. Thanks.