On a 39g, just stay on top of water changes and tank maintenance, you can go without a skimmer for a long time. Increase the frequency and % change, the skimmer is pulling waste out of your system, you can do exactly the same thing with water changes.
I would do that rather than buying a nother hang-on model if you are going to get a sump later. If "later" is a year down the road that is a bit different.
Take the skimmer off your system, take everything apart including the pump, and let it sit in vinegar water for 24hours, then take a brush and clean everything down especially the pump and the air intake. If you are not getting any foam at all, it has to be the pump or airline. You might have to buy a replacement pump. Not sure on this model, you might be able to put in a more powerfull pump and increase the skimmer performance while you are at it too.
|