Foam level fluctuates

I have a eshopps psk100 HOB, I notice that the foam level in the collection cups fluctuates throughout the day, is that normal? I have the foam level set about midway of the collection cup neck and sometimes the foam goes to the tip of the neck and when I come back later, the foam level is at the bottom of collection cup neck.

 

I have noticed the same with my HOB. Any thoughts would be appreciated.

 

Which one you have?
I checked this morning and the foam level is up at 3/4 on the the neck.

 

If there's nothing to skim, the skimmers won't skim...does this coincide with feeding?

Also, does the water level in your tank fluctuate due to evaporation? Many skimmers are sensitive to water level.

Finally, how new is your skimmer? Output can vary if the skimmer hasn't "broken in" yet.

HTH

 

Skimmer is about 1 month old

 

^+1 also, oils will interfere with skimming, so, it is common to skim less directly after feeding.

 

All of that ^^.