I just picked up my first skimmer today for my future tank. I was wondering if it would hurt anything if I set up the skimmer in fresh water just to see how it runs. Sorry this is such a stupid question.
No it won't hurt anything. I run mine in a 20 gallon tank with freshwater and vinegar to clean it. One thing you will not see is the foaming due to the density of freshwater being much lower than that of salt.