I change approx 70% of mine twice a week but I don't have a lot of fish and my tank is big. You can buy aquarium water test kits to help you figure out how much
Ammonia and nitrite spikes can be deadly for your fish. Beneficial bacteria multiply rapidly to cope with the additional organic waste being produced, which in turn cause the water to appear cloudy. The cloudiness usually last about 1-2 days till the water condition is stabilized.
Cloudy water is probably the single biggest complaint of new aquarium owners.. . In my opinion, one of the greatest inventions ever in the aquarium hobby is .