Each aquarium is biologically different from others. I have seven tanks running at present. At the moment all are crystal clear, but over the past three years I have seen one of them become slightly cloudy for several weeks, and another for a few months. Then both literally cleared overnight.
There are a lot of organics in tap water (despite the chlorine). When dechlorinator is used on replacement water, it allows the bacteria to consume these organics, and the bacteria we are here talking about can reproduce very fast compared to nitrifying bacteria.
The bacteria responsible for bacterial blooms are heterotrophs. Heterotrophic bacteria cannot synthesize their own food so they need organic material such as fish waste, dead bacteria, fish and plant matter, etc., and while some are aerobic, many are facultative anaerobes, meaning that they can survive in either the presence or absence of free oxygen. Anaerobes are organisms that do not require free oxygen for growth; this has significant consequences in aquaria. Heterotrophs appear sooner and faster. They build many of the biofilms that all bacteria use to adhere to surfaces, and they reproduce much faster, around 15 to 60 minutes, compared to hours for the autotrophs. [As a comparison, Nitrosomonas sp bacteria that use ammonia require at least twelve hours to divide, and the Nitrospira sp that use nitrite up to 32 hours.]
Heterotrophs are facultative anaerobes—unlike autotrophs which need oxygen—so they can switch between aerobic and anaerobic depending upon the environment. This is why they can kill so many nitrifying bacteria in filters when the filter is allowed to get clogged. When heterotrophs bloom in the water they switch to being aerobic and consume vast amounts of oxygen. This is the real danger of a bacteria bloom, as it can starve the fish of oxygen. Increasing aeration may be advisable in very cloudy conditions; let the fish's respiration guide you. I generally increase surface disturbance from the filter when I have slightly bacterial cloudiness.
The sudden increase in heterotrophic bacteria produces ammonia as a by-product, and the sudden surge in ammonia can overtake the nitrifying bacteria that need time to "catch up." Live plants again help here, as they can assimilate and/or take up considerable quantities of ammonia faster. Note that the bacterial bloom causes the rise in ammonia, not the opposite as some may think.
A water change is not recommended to clear a bacterial bloom. When the free-floating heterotrophs are removed, the others will reproduce even faster to compensate, thus worsening the bloom. If left alone, they usually dissipate in a few days. In an established tank, however, the source of the problem should be removed. Clean the gravel, remove decaying matter, don’t overfeed, reduce overstocking, etc. And be aware of the oxygen shortage issue.
I didn't just write all this, I copy/pasted it from some research I did on bacteria a couple of years ago, but it may help in understanding things.
Byron.