Hi...I have a Whisper Diatomagic Filter. I've only had to use it a few times and I will say that when the water is cloudy it is SUPERB at cleaning it up. The filter will remove particles as small as one micron and as such, will remove the ich organism if suspended in the water and any particulates. To my knowedge, the filter will not change your water chemistry and can be left running for a while. But...the filter is so 'powerful', that after awhile it can clog with debris and the filter will need to be rinsed and more powder added. It does not do any biologic filtration. Also, in the case of my filter, it is a hang on in the tank and does create a lot of bubbles. The last time I used it is when I changed media and the tank clouded briefly. Overall, although it is not getting much use now (since my tank cycled it has been crystal clear), I am glad I have it. If I can be of any other help. let me know. SH