So it sounds like very few of us do actual regular water changes on a regular basis, and those of us who don't change the water too often appear to have less problems. AND it is true that most "new" pond people with fresh so called clean ponds have the most trouble. I would say that that is the trouble, pond not supposed to be that clean, pond not supposed to be a "sterile" hole in the ground. What most people say is clean is really not good, as too clean can kill the good bacteria or prevent the natural beneficial bacteria and other good aquatic life, from colonizing the pond. Pond water should be "teeming" with an abundance of diverse life in order to be properly established and balanced, Trouble is that does take time, but evently it will happen, if you don't constantly change and the water or "clean the pond to death".
My brand new fish tank is all set up and now "teeming with life" . So how did this happen so quick?? Well for starter's, the gravel was old, from the old tank, and the fish ornaments we're old, not cleaned or rinsed, right out of the old dirty tank. Then the big string of floating Hornwort was dirty, had pieces of leaves, pond "sludge dust" stuck to it, so it was not clean. But the fish are all happy and no one dead yet? I got lots of new Platty fish from this pet store and that pet store, some were not in the best health and thought some would die off. But they are doing well, eating the fresh pieces of super green soft lush pond algae that I gave to them, and picking at things in the hornwort. Then the new Plattys were mixed with the old wild guppies, and all is good, cause even though tank was new, I put in some of the old fish tank water, and the dirty old gravel that I just gave a quick rinse too and ornaments, so all is good