You have a few issues here. Your water that leaves when it's turned off - that's part of what's called your 'water in transit', the problem part is what can't be contained by your lower vessel when turned off. A surge tank can remedy this, as can other solutions - but I'd have to see it. Leaving it on 25/7 can eliminate this effect - until someone has to work on it. Off or not - if it is a sterile pond, you may only need 4 hrs a day for the sanitization, if your circulation is proper. If its a single pump setup, then override the timer to get the look (if you have a waterfall or fountain) when you want it. If it's a live pond, then it really needs to run all the time. These points are all part of a proper waterfeature design. Unfortunately, in this market, lots of folks and others are creating things which have the attributes you describe - and plenty more. It's like the professor of Landscape Architecture at the University of Arizona said, 'A waterfeature that is not properly designed and/or built is a planter waiting to happen'. Good Luck!