i have installed a fountain submersible pump in my pond to use to water my garden / flowers. The discharge is 1 1/4 ". I want to reduce it to 1/2 " to connect to a water hose. Does it make any difference to
resulting water pressure if i reduce in one stage or in several stages ?
Well, from a fluid mechanics point of view, one reduction is better at least in smaller diameter piping, like going from 1 1/4 to 1/2". But pressure might suffer to where you notice it when you turn the water on if you are reducing to 1/2" at the pump and you have a distance of over say 20 or so feet to travel to the hose bib.
Now it seems like to me when I used to put in a tap for whatever, that it was so convenient I used it for a whole lot more stuff than my original intent. The first couple of times I just used the size necessary to do the job but after that I started going one size larger on pressured water piping. I mean you never know right?