Just to set the background...whitish cloudiness is either a particulate issue, or bacterial, or diatom, or organics. The particulate means there is microscopic particulate matter coming in with the tap water. The way to confirm or eliminate this type is to run a container (I would use a larger one than just a glass, maybe a 2 liter clear container) and if this is cloudy, that's the answer. Moving on to the next three, they all appear identical and can occur from within the aquarium's biological system, or arrive with the tap water. [Don't get mixed up, a diatom bloom is not related to diatoms (brown algae) as such.] Weather can cause bacterial and organic blooms. It would surprise many to realize just how much organic matter can be present in vey clear tap water; once in the aquarium and conditioned, the bacteria species that feed on the dissolved organics multiply very rapidly, each dividing into two in about 20 minutes; the more organic, the more the bacteria reproduce, turning the water hazy or cloudy.
Given your location, my first thought is that this is occurring because of the extreme heavy rains associated with Hurricane Iona a month or so ago. It could be particulate matter, or organics, or diatoms getting washed into the water reservoir. Most water authorities do not have the filtration capability to deal with this. And remember, while the particulate matter is observable (usually anyway), the dissolved organics and diatoms are not, not until they are providing food to the bacteria which we see in the aquarium water.
That explains the likely sources. These issues can be long-lived. Several years ago, Vancouver had torrential rains in the autumn (normal here, but much worse that year)and the tap water was so cloudy with microscopic suspended particulate matter that I could not see the back wall of my 18-inch width aquaria, and it lasted until the day or two before the next water change. I had dissolved organics in one tank (only) that persisted for almost three years; not bad this time, but noticeably not at all clear, compared to the other tanks in the fishroom. I never did track down any actual reason, and I discussed it with my friend Neale Monks over a period of several weeks.
Fortunately, none of these are in themselves harmful to fish. However, testing for ammonia periodically is usually advised; this does not occur from the issue itself, i.e., such blooms do not cause ammonia nor are they caused by ammonia. But the rapid die-off can sometimes apparently raise ammonia. Of course, floating plants will easily handle this, regardless, so I never tested nor worried about ammonia.
