Pool Returns Up or Down? Why This Simple Adjustment Can Improve Circulation, Reduce pH Rise, and Even Control Pool Temperature
Most pool owners—and even many pool professionals—never give much thought to which direction their pool return eyeballs are pointed.
They should.
That simple adjustment can affect circulation, chlorine distribution, pH rise, evaporation, heat loss, and even algae prevention.
The good news? It doesn’t cost a dime to optimize.
Let’s look at why this matters.
Your Pump Doesn’t Care Which Way the Return Points
One of the biggest misconceptions is that pointing your returns upward somehow gives you more circulation.
It doesn’t.
Your pool pump is producing essentially the same flow rate and pressure regardless of where the return eyeball is aimed.
The amount of hydraulic energy leaving the nozzle is basically the same.
The difference is where that energy gets used.
Returns Pointed Toward the Surface
When the return is aimed upward, a significant portion of that energy is spent breaking the surface tension of the water.
Instead of pushing water through the body of the pool, that energy creates:
- Waves
- Ripples
- Splashing
- Surface turbulence
It may look like the pool is really moving water, but appearances can be deceiving.
Surface waves are actually poor at moving large volumes of water throughout the pool. Most of the energy stays near the surface instead of circulating water to the areas that need it most.
Returns Pointed Slightly Downward
Now take that exact same return and point it slightly downward.
Instead of wasting energy creating waves, the return produces a concentrated jet of moving water beneath the surface.
That jet creates one of the most important hydraulic principles in pool circulation:
Entrainment
Entrainment occurs when a fast-moving stream of water pulls surrounding water along with it.
Think of it like a freight train.
The locomotive is relatively small, but it pulls dozens or even hundreds of train cars behind it.
The return jet is the locomotive.
The surrounding water becomes the train cars.
That relatively small stream of water ends up moving a much larger volume of water throughout the pool.
That’s where real circulation comes from.
Better Circulation Means Better Pools
When returns are aimed slightly downward, they create a slow rotating current throughout the entire pool.
Rather than constantly disturbing the surface, the water begins circulating through every level of the pool.
That moving water reaches:
- Pool floor
- Corners
- Steps
- Benches
- Tanning ledges
- Deep end
- Areas behind ladders
- Other places where stagnant water likes to hide
These stagnant areas—commonly called dead spots—are exactly where algae often begins growing.
The better your circulation, the fewer opportunities algae has to establish itself.
For most residential pools, I recommend aiming the returns slightly downward while creating one consistent rotation—either clockwise or counterclockwise—around the pool.
Better Chemical Distribution
Good circulation doesn’t just move water.
It moves chemicals.
When chlorine leaves the return fitting, you want it distributed throughout the entire pool—not remaining concentrated near the return jets.
Better circulation allows sanitizer to reach every gallon of water more evenly, helping maintain consistent chlorine levels throughout the pool.
Better Temperature Balance
Without proper circulation, pools naturally develop temperature layers.
Warm water stays near the surface.
Cooler water settles toward the bottom.
This is called temperature stratification.
Returns aimed downward continuously mix these layers together, creating a much more uniform water temperature throughout the pool.
Surface Disturbance Raises pH
Here’s something many pool owners don’t realize.
The more you disturb the surface of your pool…
the faster carbon dioxide (CO₂) escapes from the water.
This process is called aeration.
As carbon dioxide leaves the water, the pH naturally rises.
This is why pools with waterfalls, spillovers, deck jets, bubblers, laminars, fountains, and upward-pointed returns often require more acid than pools with calmer surfaces.
If you’re constantly creating surface turbulence, you’re accelerating carbon dioxide loss, which accelerates pH rise.
If you find yourself adding acid frequently, excessive surface agitation may be one of the reasons.
Surface Turbulence Also Increases Evaporation
There’s another consequence.
Surface turbulence dramatically increases evaporation.
Every pound of water that evaporates carries away a tremendous amount of heat energy.
In fact, evaporation is the single largest source of heat loss in most swimming pools.
If your goal is keeping your pool warm, minimizing unnecessary surface disturbance can help reduce heat loss.
Want to Cool Your Pool?
Now let’s flip that around.
If you live somewhere like North Texas, Arizona, Florida, or other hot climates, your pool may climb into the mid-90s during the summer.
That’s where upward-pointed returns can actually become useful.
At night:
- Aim returns upward.
- Run waterfalls.
- Operate deck jets.
- Turn on other water features.
Nighttime air is cooler than the pool water.
The increased evaporation removes heat from the pool.
I’ve personally seen pools cool several degrees overnight simply by circulating aggressively while running water features after sunset.
It’s essentially free evaporative cooling.
Just remember that the tradeoff is:
- Increased evaporation
- Faster pH rise
- More refill water
- More acid demand
Winter Is Another Exception
During freezing weather, I often recommend pointing returns closer to the surface.
Why?
Moving surface water helps prevent ice formation around:
- Tile lines
- Skimmers
- Waterline fittings
This is one of the few situations where increased surface agitation is actually beneficial.
My General Recommendation
For normal day-to-day operation, I recommend:
- Aim returns slightly downward.
- Create one slow circular rotation around the pool.
- Eliminate dead spots.
- Keep water moving through every part of the pool.
- Maximize entrainment.
- Minimize unnecessary surface turbulence.
Doing so often results in:
- Better circulation
- Better chlorine distribution
- More even temperatures
- Less pH rise
- Reduced acid usage
- Less heat loss
- Improved algae prevention
- More efficient use of your pump’s energy
Small Adjustment. Big Results.
Sometimes the biggest improvements don’t require buying new equipment.
They simply require understanding how your equipment works.
Proper pool care isn’t just about chemistry.
It’s also about hydraulics.
When you understand how water moves through your pool, you’ll prevent problems instead of constantly reacting to them.
Sometimes all it takes is turning a return eyeball a few degrees.
That tiny adjustment can make a surprisingly big difference.
Watch the Full Video
If you’d like to see these concepts demonstrated with animations and real-world examples, watch the accompanying video on this page.
If you found this article helpful, please like the video, subscribe to the Deep End Frank YouTube channel, and share it with another pool owner. Small changes like this can make pool ownership easier, save chemicals, improve water quality, and help prevent algae before it ever starts. I’ll see you in the Deep End.