Welcome to FishLore! It sounds like a bacterial bloom. When the good bacteria is gets disturbed and killed off by accident, it multiplies like mad to catch up to the demand in the tank. A bacterial bloom is the only time you "see" the bacteria in your tank. If her tank was cloudy all the time, she may not have had enough filtration in that tank. What you look for, is the gallons per hour (
GPH) rating for each filter used. Add them up, and see if you have rate of 10 times per tank size per hour if you are using
HOB (hang on back) or sponge filters, and 5 times the tank size per hour if using a
canister filter. So for your tank, you want to have 550 gph going in that tank. Some fish are bigger and messier than others, so this can also be a factor on your filtration, and how many fish you can have in your tank. Please post what you have in there, and the FishLore members can help you further.
P.S. I have a sticky here in the beginners forum called "FishLore Articles for Beginners" to help you more with cycling and other issues with a new tank.
