Clear-Ease is an excellent water clarifier for cloudy water conditions. Use if cloudy water is a problem caused by overfeeding, forgetting to rinse your gravel thoroughly, etc. It is best to leave your filter operating during use. If your water turns milky or hazy looking, that shows that the application was required and Clear-Ease is starting to take effect. After a short period of time, you should have beautiful, crystal-clear water! Clear-Ease should not be used as a substitute for regular partial water change.