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How to install a wide mouth skimmer

Updated: 16.10.2026

You have a wide-mouth through-the-wall kit and a rigid above-ground wall, and you need the order before anyone cuts vinyl. This is how to install a wide mouth skimmer so the liner is cut late and the faceplate stays intact. The [wide mouth skimmers comparison](/hub/pool-care/wide-mouth-skimmer) holds the seven prices. This page does not rank them. If water is already running down the outside, use the [stop a leaking above-ground skimmer](/hub/pool-care/wide-mouth-skimmer/sub/wide-mouth-skimmer-stop-a-leak) page. The steps follow Hayward’s Dyna-Skim manual and the Swimline 8939 manual. The Products Compared editorial team set this out on 16 October 2026. A purchase through our links can earn a commission at no extra cost to you.

You have a wide-mouth through-the-wall kit and a rigid above-ground wall, and you need the order before anyone cuts vinyl.

Our top picks

Hayward Hayward SP1091WM Dyna-Skim

Best overall

Hayward Hayward SP1091WM Dyna-Skim
9.4/10about £116.11
View offer
FixIdea FixIdea wide-mouth thru-wall kit

Alternative

FixIdea FixIdea wide-mouth thru-wall kit
9.0/10about £89.33
View offer
Hydrotools Hydrotools 8939 wide-mouth skimmer

Best value

Hydrotools Hydrotools 8939 wide-mouth skimmer
8.8/10about £67.52
View offer
On this page
  1. 1.Get the pool ready before you cut anything
  2. 2.Body, extension, then the wall
  3. 3.Screws, then the liner, then the hose
  4. 4.When you should not finish the job

Get the pool ready before you cut anything

Hayward’s manual wants about two feet of water, roughly 60 cm, before you fit the skimmer. That water holds the liner against the wall. Once you cut holes in the vinyl, the liner cannot be shifted back. A wall that already has a wide mouth needs the old plate off and the new gasket in the same place. Swimline’s 8939 manual, for a wall that is not pre-cut, describes 22 holes of 1/4 inch and an opening of 5 5/8 by 12 inches. That template belongs to that manual. FixIdea and TonGass state different openings, so a pre-cut wall should not be enlarged to match a diagram. Have a second person. A solo reach is how a gasket folds. Confirm the hole on the wide mouth skimmer buying guide before the first cut.

Body, extension, then the wall

Hayward’s manual has you assemble the wide throat to the body first, with a gasket and screws between those two parts. That joint sits outside, and once the housing is on the wall some of those screws are awkward to reach. Missing that gasket is a leak that shows when the pool is full. Hydrotools wide mouths use the same body-to-extension joint. If your kit has no separate extension, follow the parts that are actually in the box. A butterfly gasket hugs the wall only. A two-piece set puts one gasket outside the wall and one under the faceplate, on the liner. Foam, a folded corner, or a liner flap in that joint will weep. Hayward’s product page says you should not need silicone if the correct gaskets are fitted. Put the housing on the outside, line the faceplate on the inside, and start the screws by hand so the threads find the holes.
Hayward Hayward SP1091WM Dyna-Skim

Testsieger

Hayward Hayward SP1091WM Dyna-Skim
9.4/10about £116.11
View offer

Screws, then the liner, then the hose

Fit every faceplate screw before you tighten any of them, in a cross pattern, so the plate comes down even. Stop while the plastic is sound. A cordless drill is how these ABS plates crack. Hand tight, then a small nip with a screwdriver, is the limit these sources support. Cut the vinyl only after the plate is seated, and only inside the opening. Hayward’s return hole is 2.38 inches, plus or minus 0.03 inch, and that liner cut waits. Swimline says no glue on the threads, and the eyeball should aim away from the mouth. With the pump on, the water should sit about midway up the faceplate or the pump can lose prime. The floor still needs a vacuum. If a drip appears as the water reaches the joint, stop and use the leak page.

When you should not finish the job

Stop if the steel is rusted, crushed by ice, or soft under the gasket. A new skimmer will not hold a panel that has already failed. Stop if you need a new opening in steel and you do not have the tools or a second person who has done it. Stop if the pool is soft-sided, or still under a warranty that forbids extra holes. The manuals used here describe rigid walls. Call a wall repair if the loss is faster than a faceplate weep, or if a cracked plate will not hold screws. HSE’s HSG179 does not apply to a private domestic pool used only by the household and guests. A skimmer from a trader still has to match its description under the Consumer Rights Act 2015. The job is finished when the pump holds prime and the wall under the plate stays dry.

Common questions

Do I fit the wide throat before the housing goes on the wall?
On a Hayward-style wide mouth, yes. The extension gets its own gasket and screws before the body meets the wall. That joint is hard to reach later. If your kit has no separate throat, use the parts in the box. Swimline’s 22-hole template is only for a wall that is not already cut.
Which gasket goes where?
A butterfly gasket hugs the wall, with no foam in the joint. A two-piece set puts one gasket outside the wall and one under the faceplate. Hayward and Hydrotools wide mouths also need the gasket between body and extension. A FixIdea reviewer expected two and was unsure what arrived, so read the kit you have.
Can I use a drill on the faceplate screws?
Start every screw by hand, in a cross pattern, and stop before the ABS cracks. Reviews describe power drivers stripping the plate. A screwdriver for the last nip is as far as these manuals support. There is no single torque you can copy from one brand onto another.
When do I cut the vinyl, and where does the eyeball point?
Trim only the vinyl inside the mouth, after the plate is even. Hayward’s return hole is about 2.38 inches, and that liner cut waits. Aim the eyeball away from the mouth so the return does not blow leaves off the weir. Swimline says no glue on the threads. A weeping adapter is a leak-page job.
When should I stop and call a wall repair?
Stop if the steel is rusted or crushed, if the new cut is beyond your tools, or if a soft-sided pool’s warranty forbids holes. Stop too if water keeps leaving once the level is below the mouth. A cracked faceplate will not seal with another quarter-turn.

Related pages

Wide mouth vs standard skimmer

Wide mouth skimmer

Best wide mouth skimmer for a measured UK pool wall

Wide mouth skimmer buying guide: measure the cutout

Above ground skimmer leaking at the faceplate joint

Sources

Manufacturer pages, GOV.UK, and HSE, plus the sizing note marked as a US shop. Prices and ratings are amazon.co.uk listing lines. Retrieved 16 October 2026.

  1. Hayward Dyna-Skim manual IS1091LX (retrieved 16 October 2026)
  2. Hayward SP1091WM Dyna-Skim wide mouth skimmer (retrieved 16 October 2026)
  3. Swimline 8939 wide mouth skimmer installation manual (retrieved 16 October 2026)
  4. Plastica above-ground pool widemouth skimmer, The Pool Cleaners (retrieved 16 October 2026)
  5. HSE HSG179 — Managing health and safety in swimming pools (retrieved 16 October 2026)
  6. Consumer Rights Act 2015, GOV.UK (retrieved 16 October 2026)
  7. Pool Factory — leak on a through-wall skimmer (retrieved 16 October 2026)
  8. Royal Swimming Pools — above-ground skimmer sizing (US shop; not a UK price) (retrieved 16 October 2026)
  9. amazon.co.uk listings for the seven ASINs in this comparison (retrieved 16 October 2026)