I setup my first pond last year. I guess I did OK (with tons of help from this forum) because although I introduced too many fish at the same time, I had no casualties. Well, until yesterday when the skimmer “flap” was stuck down and a Koi swam into the skimmer and died. Poor guy survived our New England winter just fine 
But I did make one mistake. My pipes froze and blew up. My pond is built on a hill (no choice for location). It is part above-ground and part below-ground. The plumbing is PVC. Getting water to flow where I wanted required a Phd in physics (which I don’t have) so it was a lot of trial and error.
This was my first time working with PVC. I love the stuff! It’s very easy to fix mistakes by just cutting the pipe. Only thing, in order to connect a new fixture, the cut has to be fairly straight. It can be a little off, but too much and it won’t seal with a coupler. If you have enough clearance, I would guess that a hacksaw is best for this. If you are impatient (or make a lot of mistakes, like myself) a power tool is desirable. For me, the perfect tool was a portable band saw from Harbor Freight. If you have the clearance, it gives a great cut. For my system, it meant holding it in all kinds of unsafe positions. If you go that route be very careful (though I hear the probability of successful reattachment is higher with a band saw cut … just sayin
If you live in a climate where temperatures reach freezing, make sure that there are fixtures that will allow you to drain the pipes for the winter. I did this, but my pipes still blew up. Because of all the different “levels”, much of the water didn’t drain. This was an opportunity for me to cut out the fixtures that did nothing but remind me of how uncooperative water is. But you may not feel the same way. This time, I installed a few rubber couplers at strategic places. Next winter I’ll just unclamp them and pull the pipes apart.
Hope this helps someone!
But I did make one mistake. My pipes froze and blew up. My pond is built on a hill (no choice for location). It is part above-ground and part below-ground. The plumbing is PVC. Getting water to flow where I wanted required a Phd in physics (which I don’t have) so it was a lot of trial and error.
This was my first time working with PVC. I love the stuff! It’s very easy to fix mistakes by just cutting the pipe. Only thing, in order to connect a new fixture, the cut has to be fairly straight. It can be a little off, but too much and it won’t seal with a coupler. If you have enough clearance, I would guess that a hacksaw is best for this. If you are impatient (or make a lot of mistakes, like myself) a power tool is desirable. For me, the perfect tool was a portable band saw from Harbor Freight. If you have the clearance, it gives a great cut. For my system, it meant holding it in all kinds of unsafe positions. If you go that route be very careful (though I hear the probability of successful reattachment is higher with a band saw cut … just sayin
If you live in a climate where temperatures reach freezing, make sure that there are fixtures that will allow you to drain the pipes for the winter. I did this, but my pipes still blew up. Because of all the different “levels”, much of the water didn’t drain. This was an opportunity for me to cut out the fixtures that did nothing but remind me of how uncooperative water is. But you may not feel the same way. This time, I installed a few rubber couplers at strategic places. Next winter I’ll just unclamp them and pull the pipes apart.
Hope this helps someone!