Got a question, my skimmer box keeps emptying out by itself. Is it supposed to do that?, I have noticed that lately. It never did that before, until after I cleaned the pond back in June.
First of all, turn off the pump, fill up the pond and let it sit for a day. If the water stays at the same level, you have water escaping somewhere.
Turn the pump back on. Check to see if there is a tiny dripping off the waterfall. You are losing water somewhere and that's the most likely place.
Maybe your pond has settled and the water is going over the side? This does happen over the years.
Or you could have a small liner leak....very rare, but possible.
To find out what is happening, either remove the pump from the skimmer box and put it in the pond. Run it without water going through the skimmer. If it works without losing water that way, you probably have a leak in the seal where your skimmer is attached to your liner. That happens often.
If you don't want to remove the pump from the skimmer, use another pump in the pond. Turn the one in the skimmer off and run the other one. If you don't lose water, you know the problem is with the skimmer.