Choose a warm day with no rain or clouds. This is very important. When it is warm and sunny, the liner fits into place with ease.
Pump every drop of water out of the pool. Then remove the old liner. Next, add some pool sand to re-groom the base.
An industrial broom works well to smooth base.
Remove all top rails to expose your bare pool walls. Unfold the liner & center in the middle of the pool. Evenly spread out, ignoring the seams. The liner will not go all the way to the pool wall. There will be a space between the edge of the liner and the wall, allowing room for the liner to stretch into place.
*Do Not Skip This Step. This is where 90% of installation mistakes occur.* Once the liner is centered, you will need to temporarily attach 4 points of the liner to the pool wall (North, South, East, West). This will ensure your liner is perfectly even all the way around. If you only start with one point and start attaching the liner by working your way around the pool, the liner will not be straight and may seem short or too small for the pool.
Once your liner has your 4 direction points attached to the walls, add 4 more in between those points and attach (Northwest, Northeast, Southwest, Southeast). You may now attach the liner with coping, or into the bead receiver, all the way around the pool.
Add your top rails and metal back on. The liner is now center and aligned. The liner may feel tight, but this is normal. The liner will stretch into place during the vacuum and filling process.
The liner may feel tight, but this is normal.
After installing the liner to the wall, add your shop vac to the open skimmer hole and push the vac hose down to the sand. Then duct tape the open space at the skimmer and return jet for an air tight seal. Plug the vac into a safe (GFCI) outlet. When you turn the vac on, if there are any wrinkles, or desired adjustments with the liner, manipulate them by hand before filling.
As the vac runs, and the liner is adjusted to your likeness, you can start filling the pool with water. You think your work is done, but it is not done yet. Fill during hot and sunny hours only. Fill only when someone is home to check on the filling process every 20 minutes until the pool is half way full. If something loosens, pulls inwards, or slips at the top, turn everything off, adjust, tighten clamp down, and resume filling.
Check filling process every 20 minutes until the pool is half way full.
The shop vac continues to run until the pool is half way full. As it fills, pull the vac hose up a little bit at a time so that it stays above the water level in the pool. When the water reaches the half way point, eliminate the vac by pulling the hose out of the pool wall. Then cut the holes for your plumbing pieces including the skimmer box and return jet.