what hang-on back skimmer is quite?im thinking of getting a cpr bak-pak or a remora, which one is quite,any suggestions of any other good quite skimmer for a 20 gallon
Deltec MCE 300 is new but big enough for a 20 gallon.. The Deltec MCE 600 is good and quite if you really want to spend $500 on a skimmer for a 20 gallon. I like the AquaC's for smaller tanks but make a hissing sound that can be annoying.
Personally, I think that you're better off going skimmerless on a 20 gallon since it's so easy to do high percentage water changes. You can run carbon in a hang on back filter. Replace the carbon weekly and do a 5-10 gallon water change weekly and you're good to go. If you absolutely positively have to have a skimmer then the remora pro is a decent choice for a 20.