It could also be something to do with it being a Perigee Full Moon tonight and not the water at all. The moon will appear 14% bigger tonight than normal. The word 'Lunatic' is actually derived ( in Latin ) from the same word for moon ( lunar ..
Another thing, is weeds. Not sure if you have sprayed weeds, but if you have, what you'll know is that you might kill the old ones, but almost straight away new weeds which you struggle to recognize establish themselves. Sometimes I wonder if you are better leaving the old ones in place. At least you know where the prickles will be..