I know that this has been covered here before, that's how I learned how to do it , but I wanted to share my through-wall skimmer install on my Intex 18' x 48" Ultra Frame AGP.
It was really as easy as it looks, if you are at all considering it, just do it. Take your time, double check everything. I'll admit it, I was very hesitant to take a razor blade to my pool liner!!
I used the Hayward SP1091LX skimmer as many here have had previous success with them.
I drained the pool to about 1" below the skimmer location. I know that some have installed without draining, but I didn't want to take any chances, and the lawn needed some water anyway.
I carefully split the butterfly gasket, then trimmed the leftover material from the split with a sharp razor. This needs to be done carefully.
Next I placed the inside flange in its location, leveled it as best I could, and duct taped it in place. I took my Philips screwdriver (and a deep breath) and did this to my new pool:
Be sure to support the liner with your fingers as you slowly push the screwdriver through the liner, turning it slowly as you push. I started with the top center hole, then the bottom center hole, then evenly around the outside putting a screw in each hole as I made them to keep the flange in place.
I removed all the screws, then placed the inside gasket against the flange, and passed a screw thru the top center hole to keep the gasket in place. I then screwed the flange/gasket to the liner, putting the screw about 3/4 of the way thru leaving the gasket loose to line up the holes. I went around the flange installing all the screws about a 1/4 of the way thru, being careful to pass thru all the holes in the gasket.
I then mounted the outside gasket over the screws sticking out, then carefully mounted the skimmer starting with the top center screw, then the bottom left & right screws, then the remaining screws evenly across. I went around the screws three or four times, tightening a little at a time evenly. When you finally tighten it down completely be careful you do not distort the flange and gasket. I tightened until I saw the gasket squish out very slightly then backed off until the squish went away. Sorry I didn't get any pics of these steps, I was a one man operation LOL!
Here it is, right after I cut out the liner. You can see in this picture that even though I was very careful to level off the flange, somehow while I punched though the liner I slightly canted the frame. The skimmer seems to work just fine however.
I cut the liner last, after all the plumbing to the skimmer was done.
I hard plumbed the skimmer & original suction port using 1-1/2 PVC. I put ball valves for isolation and a union incase I should ever need to disassemble something. I plan to use the original port as a vacuum port now. I connected to the original Intex fitting using the 1-1/2 PVC electrical box adaptor as recommended here at TFP. I used the nut from an older plunger valve because I liked the fact that I could put it on after the cement dried. Also, if you are very careful you can use the gasket from the plunger valve as well, it's a close enough fit but a hair larger than the inside opening of the port. If you are persistent you can get it to stay in the port properly.
I used a Game A2656 40MM X 1-1/2 Short Adapter for the Intex hose hookup.
To keep water out of the original suction port (I was not draining that low) I used a 1-1/2" adapter and hose from an old Intex skimmer on the port & and lifted the other end of the hose out of the water. Worked great to keep the connections dry while the cement set. (LOL I just noticed the stick floating by, hence the skimmer install).
On the Return port side I installed the 1-1/2" Hayward return that came with the skimmer. I though it would be best to have a standard fitting. It has a 3/4" eyeball, but I am going to change it to 1" to lower the filter pressure a bit.
I then hard piped with 1-1/2" PVC and ball valve. I had to get creative with 45's as I ran out of 90's. I used the second 40MM adapter at the other end.
Here it is, all hooked up and refilling while I let the cement dry good!
Skimmer works great so far and no leaks!
I hope this helps someone interested in doing this. It was super easy, just take your time. Once the pool was drained it only took me about 3 hours, and that's with double and triple checking everything.
Next, solar heating !!