Installing Your Pool, Stage 6: Installing The Liner

Where you are: cove built, sand base finished, uprights standing. If you are not there yet, go back to stage five.

What you will have finished with: liner hung and seated, joiner plates on, water partway up the pool, and the return fitting installed.

This is the stage with real technique in it. Not difficulty, technique. Nothing here is heavy or dangerous, but the order matters, the temperature matters, and there is one irreversible moment near the end.

Read this before you start

This stage cannot be paused. The vacuum is what holds your liner against the wall, and your assembly instructions say to fill the pool to the base of the wall before stopping and removing the vacuum. So from the moment you switch that vacuum on, you are committed to getting water in the pool.

Plan for a full afternoon with nothing after it.

Pick a warm, sunny day. This is not in your instructions and it is the single most useful thing anyone can tell you about liner installation.

Vinyl is stiff and unforgiving when it is cool, and stretchy and cooperative when it is warm. The same liner that fights you at nine in the morning will drape itself into place at two in the afternoon in the sun. Installing cold is the most common reason people end up with wrinkles they cannot remove.

If you can, leave the liner in its box in direct sun for an hour or two beforehand.

Have two or three people. One inside, one or two outside working around the wall.

What you need

A shop vacuum with a hose that will reach
Duct tape or similar
Light, flat-soled shoes for everyone
A garden hose ready to go
Large pliers, for the return fitting later
A sharp blade, which stays in your pocket until the very last step

Phase 1: Set up the vacuum

This is the trick that makes the whole stage work, and it is straight from your instructions.

Insert the vacuum hose down into the pump return hole, from outside the pool, so that it reaches to about 6 inches from the ground on the inside.

Tape the hose in place so it cannot slip.

Tape the skimmer hole shut, on the inside. Your instructions are explicit about this, and it is the step people forget. If air can leak in through the skimmer, the vacuum cannot pull the liner tight and the whole method stops working.

What this does: once the liner is hanging, the vacuum pulls the air out from behind it, sucking it firmly against the wall and drawing wrinkles out of the floor as it goes. It is remarkably effective and it does most of the work for you.

Phase 2: Position the liner

Place the unfolded liner in the centre of the pool area, at right angles with the skimmer hole. That alignment is specified in your instructions, and getting it right now saves a lot of adjustment later.

Everyone in flat-soled shoes. Your instructions warn that the slightest heel mark could be visible once the pool is filled. That is not an exaggeration, and the base you carefully finished in stage five is easy to ruin in a careless minute.

Check the orientation before you unfold. Two ways to tell, both from your instructions:

The side with the protruding seam faces downward
The patterned side faces upward

Get this wrong and you will find out at the worst possible moment.

Unfold carefully, bringing the bottom sidewall seam close to the base of the wall as you go. Work it out evenly rather than dragging it into place.

Phase 3: Hang it

How you do this depends on which liner you have. Our liner comparison guide explains the types if you are not sure what you bought.

U-bead

Hang the liner on the top of the wall and install the round stabilisers to secure it.

Straightforward, and the bead does the aligning for you.

Overlap

More adjustment involved.

Lift a section of the liner over the top of the wall, adjusting the tension so you get 1 to 2 inches of stretch in the wall, then secure it with a plastic coupler. Work around the pool doing this.

Your instructions anticipate the problem you will run into: at some point the liner will be either too tight to drape properly, or too loose. The fix is to remove some of the couplers and redistribute the tension, rather than forcing it.

Expect to do this more than once. It is normal, not a sign you have done something wrong.

Phase 4: Fit the joiner plates

With the liner hung, install the joiner plates on top of each upright, then fit metal screws at the top of the support posts.

Your instructions add an important condition here: make sure the support posts are perpendicular to the ground as you do it. This is your last chance to correct a post that is leaning. A post out of vertical now becomes a top seat that will not sit properly in stage seven.

Check each one as you go rather than at the end.

Phase 5: Start filling

Now put water in.

Fill slowly. A gentle flow gives the liner time to settle and gives you time to work.

While the water is shallow, work the wrinkles out. This is not in your instructions but it is the difference between a good floor and a mediocre one. In clean flat-soled shoes or socks, walk the floor and push wrinkles outward from the centre toward the walls, using your feet only. Never a tool, never anything sharp.

Your window is small. Once the water is more than about knee deep, it is pinning the liner and you have lost the ability to move it. Small wrinkles are cosmetic and plenty of pools have a few. Deep folds collect grit and are a common origin point for leaks years later, so if you have them and the water is still shallow, deal with them now.

If things go wrong here, our post on wall buckling and liner wrinkles covers the fixes.

Watch the wall as it fills. If anything starts to deform, turn the water off and assess before adding more.

Leave the vacuum running.

Phase 6: Stop, and remove the vacuum

Your instructions are specific: fill the pool up to the base of the wall before stopping and removing the vacuum cleaner.

By that point there is enough water holding the liner in place that it no longer needs suction. Remove the vacuum too early and the liner can pull away from the wall.

Phase 7: The return fitting, and the one irreversible step

Now install the return fitting, and this is the part to slow down for.

The sequence in your instructions exists for a reason, so follow it exactly:

Place the return fitting ring against the liner and adjust it so it is perfectly aligned with the hole in the wall.
Secure it in position.
Only then, cut the liner in the middle of the ring.

That order is everything. The ring positions and secures first, and the blade comes out last. Cutting a hole in a hung liner before the ring is aligned is the one mistake in this entire installation that cannot be undone with patience.

Then:

Insert the return fitting from the inside, with the first gasket between the return fitting and the liner, and the second between the wall and the liner.
Tighten the outside ring with large pliers, taking care not to crease the liner.

Firm and even. A creased liner at the fitting is a leak waiting to happen.

If you have a bottom drain, the principle is the same: find the holes through the middle of the liner, screw the ring and gasket in against the liner, cut the liner in the middle of the ring, then screw on the drain cover. Ring first, cut second, always.

What good looks like

Liner sitting smoothly against the wall with no significant sagging
Floor reasonably free of deep folds
No footprints or heel marks visible through the vinyl
Liner secured all the way round, evenly tensioned
Joiner plates on, posts perpendicular
Water at the base of the wall or above
Return fitting installed, aligned, and not creased

Before you move on

Warm sunny afternoon chosen, full session available
Liner warmed in the sun beforehand
Vacuum hose down the return hole to about 6 inches from the ground, taped in place
Skimmer hole taped shut
Everyone in flat-soled shoes
Liner centred and at right angles with the skimmer hole
Protruding seam facing down, pattern facing up
Liner hung: stabilisers for U-bead, couplers with 1 to 2 inches of stretch for overlap
Tension redistributed as needed rather than forced
Joiner plates and screws fitted, posts perpendicular
Filled slowly, wrinkles worked out while shallow
Water up to the base of the wall before the vacuum came out
Return ring aligned and secured before cutting
Both gaskets in the right places, outside ring tightened without creasing

The short version

This stage cannot be paused. Allow a full afternoon.
Install on a warm sunny day. Cold vinyl will not cooperate and this is the main cause of permanent wrinkles.
Vacuum hose down the return hole to about 6 inches from the ground, taped in place, and tape the skimmer hole shut.
Centre the liner at right angles with the skimmer hole. Seam down, pattern up.
U-bead hangs on the wall with round stabilisers. Overlap uses couplers with 1 to 2 inches of stretch, and you redistribute tension by removing couplers rather than forcing it.
Fit the joiner plates with the posts perpendicular to the ground.
Fill slowly and work wrinkles out with your feet while the water is still shallow.
Fill to the base of the wall before removing the vacuum.
Align and secure the return ring first. Cut the liner last. That is the one step you cannot undo.

Next in this series: top seats and seat caps. With the liner in and water going up, the pool finally starts looking like a pool.