overskimming???

[sphelps]

You can over skim depending on what you're keeping. It's always better to have something on the larger size since most skimmers are under rated but overkill isn't always a good thing.

I run my skimmer on a half duty cycle overnight as running it 24-7 was causing problems.

On the tank size in question I wouldn't even run a skimmer, the volume is too small. Weekly water changes will be more than adequate.