Return jets (also called inlets or return fittings) are the openings in the pool wall that send filtered, treated water back into the pool. They determine how water circulates, where debris drifts, and whether dead zones develop. A properly aimed return jet pushes floating debris toward the skimmer and ensures even water distribution throughout the entire pool.
Last updated: 2026-03-22
What does a return jet actually do?
The return jet is the final point in the water loop. After filtration, disinfection, and optional heating, water travels through the return plumbing back to the pool. The return jet sits in the wall, usually 30 to 50 cm (12 to 20 inches) below the waterline, and features an adjustable eyeball fitting that lets you control the direction of the water stream.
The jet creates flow inside the pool. Without that flow, water would sit still and chemicals, heat, and debris would distribute unevenly. A well-aimed return jet keeps the entire pool volume in motion.
Standard return jet diameter is 1.5 inches (38 mm) or 2 inches (50 mm). Flow rate per jet depends on pump output and the number of inlets: with a pump rated at 8 m3/hr (35 gpm) and two return jets, each inlet delivers about 4 m3/hr (18 gpm).
Types of eyeball fittings
The eyeball fitting is the component you screw into the return jet housing to control water direction. Three common types exist:
Adjustable ball eyeball fitting
This is the most popular type. A rotating ball inside a housing lets you aim the stream in virtually any direction. You can turn it by hand without tools. The opening is typically 10 to 15 mm (0.4 to 0.6 inches) wide.
Fixed-direction fitting
A cheaper alternative without an adjustable ball. The stream always goes straight forward. This type appears mainly in basic above-ground pools. The downside: you cannot fine-tune circulation.
Venturi fitting with air intake
A specialised fitting with an additional air-intake port that uses the Venturi effect. Water mixes with air bubbles, raising the dissolved oxygen level in the pool. Useful at water temperatures above 28 degrees Celsius (82 degrees Fahrenheit) when oxygen depletes faster. The trade-off: the air intake reduces effective water pressure by roughly 10 to 15%.
| Fitting type | Adjustable | Air mixing | Price range |
|---|---|---|---|
| Adjustable ball eyeball | Yes, 360 degrees | No | €5–15 / $6–18 |
| Fixed-direction | No | No | €3–8 / $4–10 |
| Venturi fitting | Yes, limited | Yes | €10–25 / $12–30 |
How to set return jets for optimal circulation
The ideal setup creates a slow rotational flow pattern that pushes debris toward the skimmer. Follow these steps:
- Aim all return jets in the same direction along the wall, so the water rotates clockwise or counter-clockwise. Choose the direction that drives debris toward the skimmer.
- Tilt the eyeball fittings 10 to 15 degrees downward. This creates a downward current that also moves water along the pool floor.
- Never point a return jet straight at the skimmer. The counter-current prevents debris from entering the skimmer.
- Test circulation by dropping a few drops of food colouring near the return jets. Within 3 to 5 minutes the colour should visibly move toward the skimmer.
Tip
In summer, when your pool sees heavy use, angle the return jets slightly more toward the surface. Floating debris from sunscreen and skin cells will reach the skimmer faster.
For a rectangular pool measuring 8 x 4 metres (26 x 13 feet) with the skimmer on a short wall, place the return jets on the opposite short wall. Aim them slightly left or right (not straight ahead) to create an oval flow pattern.
How many return jets does your pool need?
The right number of return jets depends on water volume and pool shape. Too few jets means poor circulation and dead zones. Too many jets reduces pressure per inlet, making each stream too weak.
| Pool volume | Minimum jets | Recommended | Placement |
|---|---|---|---|
| Up to 15 m3 (4,000 gal) | 1 | 1–2 | Opposite the skimmer |
| 15–30 m3 (4,000–8,000 gal) | 2 | 2 | Distributed along the long wall |
| 30–60 m3 (8,000–16,000 gal) | 2 | 3 | Two on the long wall, one on the short wall |
| 60–100 m3 (16,000–26,000 gal) | 3 | 4 | Evenly distributed, opposite skimmers |
The rule of thumb is 1 return jet per 15 to 20 m3 of water volume. Keep at least 1.5 metres (5 feet) between two return jets for even distribution.
What are dead zones and how do you fix them?
Dead zones are areas in the pool where water barely moves. You can spot them by localised algae growth (a green patch in a corner), cloudy water in one specific area, or uneven temperature distribution (cold spots).
Common dead zone locations include corners far from the return jets, the area behind pool steps, and the deepest point when return jets are aimed too horizontally.
Three solutions:
- Re-aim the return jets: point an eyeball fitting directly toward the dead zone. Often a small adjustment of 10 to 20 degrees is enough.
- Add an extra return jet: for large pools or irregular shapes, an additional inlet may be the only solution. Budget roughly €150 to €300 ($175 to $350) for installation.
- Increase pump speed: if you have a variable-speed pump, you can temporarily increase flow rate. But be aware: energy consumption rises with the cube of the speed. Doubling the speed requires eight times the power.
Tip
Drop food colouring in a suspect corner while the pump is running. Does the colour move toward the skimmer within 5 minutes? Circulation is adequate. Does it stay in place? You have found a dead zone.
The Venturi effect in return jets
The Venturi effect occurs when water passes through a constriction: velocity increases and pressure drops. In a Venturi return jet, an extra air port sits at the narrowest point. The reduced pressure draws outside air in, mixing it with the water stream as tiny bubbles.
This has two advantages. First, it raises the dissolved oxygen level in the water, which is important at temperatures above 28 degrees Celsius (82 degrees Fahrenheit) when oxygen escapes the water faster. Second, the bubble stream is visually appealing, creating a spa-like effect.
The disadvantage: the air intake reduces effective water pressure by 10 to 15%. The jet’s reach becomes shorter, which can hurt circulation in larger pools. Use Venturi fittings as a supplement, not as your only return jet.
Return jets in above-ground vs in-ground pools
In above-ground pools, the return jet is usually integrated into the filter housing on the wall. You typically have just 1 return jet and 1 skimmer, either in the same unit or placed close together. Aim the eyeball fitting along the wall to create a spinning current. This works well in round pools; oval models tend to develop dead zones at the narrow ends.
In in-ground pools, return jets are built into the concrete shell or fitted through the liner. Their position is determined during construction and is difficult to change afterward. Standard placement is 30 to 50 cm (12 to 20 inches) below the waterline, opposite the skimmer. Concrete pools can have extra return jets added relatively easily. Liner pools are trickier because you need to cut through the liner and create a watertight seal.
Standard plumbing diameter for return jets is 50 mm (2 inches) in in-ground pools and 38 mm (1.5 inches) in above-ground pools. A larger diameter means less resistance and higher flow per return jet.
Maintaining your return jets
Return jets require minimal maintenance, but a few checks each season prevent problems:
Monthly: verify that eyeball fittings are still securely seated. Water flow can gradually loosen them. A loose fitting reduces flow velocity and can fall into the pool.
At season start: remove the eyeball fittings and inspect them for calcium buildup. In hard water (above 250 mg/l calcium), scale can narrow the opening. Soak them for 30 minutes in a solution of 1 part white vinegar to 3 parts water to dissolve deposits.
At winterisation: blow out the return plumbing with compressed air and install winter plugs in the return jet housings. This prevents frost damage. A cracked return jet from freezing costs €50 to €150 ($60 to $175) to replace, not including labour.
Want to understand how return jets fit into the complete system? Read how a pool works . For information about the skimmer on the other side of the loop, see pool skimmer . And for everything about the plumbing that connects the return jets, check pool plumbing .
Frequently asked questions about return jets
What direction should I point my return jets?
Aim the eyeball fittings slightly downward (10 to 15 degrees) and sideways along the wall, so the water forms a circular rotation pattern. Never point them straight at the skimmer. The goal is to push floating debris toward the skimmer through the rotating current.
How many return jets does my pool need?
The rule of thumb is 1 return jet per 15 to 20 m3 (4,000 to 5,300 gallons) of water volume. A 30 m3 (8,000 gallon) pool needs at least 2 return jets. Pools of 60 m3 (16,000 gallons) or more need 3 to 4, distributed along the wall opposite the skimmer.
How do I identify and fix dead zones?
Dead zones are areas where water barely moves, recognisable by localised algae growth or cloudy water in a corner. Fix them by re-aiming the return jets, adding an extra jet, or increasing pump speed.
What is the Venturi effect in return jets?
Some return jets have a Venturi opening that draws in air and mixes it with the water stream. This raises oxygen levels in the pool and creates a visible bubble trail. The Venturi effect is most useful in warm periods when dissolved oxygen drops more quickly.