What Makes A Fish Tank Cloudy

I have a 20 gallon fish tank with 3 fancy gold fish in it. Lately my fish tank has been so cloudy.?

I am not sure what to do for it. I dont want to put my fish in harm by making them live in a cloudy tank. I just took out some water and cleaned the tank. But it still hasnt gotten better. If anyone had this type of problem and found a way to make the water clear again let me know. Thanks!
I have a gravel siphon
I change the filter on a regular basis whenever i see it needs to be changed

The cloudiness you are seeing is from a bacterial bloom. This is caused by a bit more ammonia being in the tank than the bacteria can handle and that caused them to multiply very quickly. The very best course of action for you is to check the ammonia level to be sure it’s not way too high and change some water if needed to reduce that level, but otherwise do nothing. Before long the bacterai will start growing on the surfaces of the tank and filter and will die off in the water column. When this happens the tank will clear up. To be quite honest, the most common cause of this problem is over cleaning. Do your regular water changes (25% once a week) and rinse out the filter in the old tank water as you do. Once a month replace the filter cartridge. Wipe the inside of the glass and rinse and orniments that appear to need it, but otherwise don’t clean too much. The more you clean the more bacteria you remove and the more likely this is to happen again.

It’s really nothing much to worry about and should clear up in a few days.

MM

50 gallon oscar tank