Not sure on anyone's personal history yet but I do know that if you immediately write off high water pressure from the irrigation system you are potentially losing the chance to cut a few hours of cleaning. To drop a blanket statement like "high pressure is destructive to ponds" is just lazy and not true.
There are plenty of uses for high pressure. Just to name a few... You can fill up tubs, pools you have already cleaned, or any kind of basin, and drop a pump into this basin with 2in hose and use it to get much more flow than any garden hose, without having a focused line of pressure. This is useful for multiple things I won't even bother listing. You can use a nozzle on the tip of a garden hose to get decent pressure without as much as a pressure washer to get algae off liner, string algae off rocks on waterfalls in cracks a brush would not reach, etc. In many cases tapping into the irrigation bypasses the water meter saving the client a nice bit on their water bill. And honestly the most important is filling up the pond to a point where you can put fish back in and leave, you can stick the hose in any kind of way so that the pressure will not disturb anything and it will fill much faster with the high pressure from the irrigation instead of the crap pressure from the side of the house. These are just a few things, I have about a hundred different tricks that are all situational.
If you close your mind to things immediately you are missing out on being innovative and finding new, effective solutions.
Jakk
