I have been running my system for a little over a year. I do 25% water changes every two weeks. My system is sumpless as well. I AM however going to be adding a skimmer. My biggest fear I guess is an overall system crash....don't know why. My fish are starting to get large and when I see them poop I am amazed how much bigger thier dumps are getting. I will be adding a hang on so Idon't think it will make a big difference either way...maybe help a little. Anyone have a hang on skimmer they want to sell???
