So I put together a new 20g tank yesterday, and this is what it currently looks like:
Super cloudy water. This is one of those things that triggers new people in the hobby to "clean" their tanks.
They'll do a biiiig water change to clear up the water, only to find that the cloudiness returns even WORSE by the next day. Which means something must be wrong with the substrate or the wood, right? Water that is this foggy can't possibly be a good sign for the health of the tanks, right???
The white cloudiness in these cases is caused by a sudden increase of bacteria [as opposed to green cloudiness, which would indicate an algea bloom]. These bacterial populations are not the same as the bacteria you grow when establishing the nitrogen cycle, but they are a sign that the process is underway! They boom in numbers when there is a sudden excess of nutrients. You actually don't want to mess around with your tank at all when the water looks like this. Replacing the water may only bring in a new wealth of nutrients, prolonging or intensifying the cloudiness (the water may look more clear immediately after a water change, but will become cloudy again as the bacteria repopulate the water column).
What will happen is, if you leave it alone, the denitrifying bacteria that you actually want in your tank will outcompete this cloudy bacteria once the cloudy bacteria runs out of excess nutrients to consume. At which point, your tank water will clear up, and your nitrogen cycle will be well under way of establishing itself♡
So once again, the best course of action wrt to this cloudiness in a new [and fishless] tank is to do nothing😁
On the other hand, if you DO you have fish during this stage, you'll need to make sure the water column well oxygenated at night after the lights go out, because this murky bacteria uses up a lot of oxygen, and the plants don't produce much oxygen at night while the lights are off
Also check your perameters [ammonia, nitrite, nitrate] daily. If your ammonia is spiking, ideally, you'll want to move the fish into a different holding tank [which I will likely need to do for my temporary guppy residents here in a day or two--I have a plant holding tub with an established cycle that I'll be moving them to]. But if you don't have that option, then you'll have no choice but to do some water changes--which will prolong the cloudiness but is absolutely required for the health of your fish😔
If your tank was previously cycled already and suddenly becomes cloudy like this, test your perameters [ammonia, nitrite, nitrate]. This cloudiness may be an indication that your cycle has crashed and the bacteria are needing to repopulate your tank again (and are in the process of doing so). There are excess nutrients causing the bacteria to bloom and produce this cloudiness, and the denitrifying bacteria needs time to catch up in numbers and outcompete them.
okee, that's all for now.
As tax, here's a picture of Hugh's tank today!