Why Do Bubbles Appear in Pool Return Jets?

Bubbles consistently appearing in your pool's return jets are most commonly a symptom of low water level, which allows the skimmers to draw in excess air into the filtration system.

Understanding Unwanted Pool Bubbles

When you observe a stream of bubbles emanating from your pool's return jets, it's typically an indicator of air being introduced into your pool's circulation and filtration system. These are generally unwanted bubbles, distinguishing them from bubbles created by features like spa jets or aerators.

The primary mechanism behind these bubbles, as highlighted by pool maintenance observations, is straightforward:

• The Most Common Reason: Low Water Level
  • The most common reason why bubbles blow through the return jets is that the water level is too low.
  • When the water level in your pool drops below the optimal height (typically the middle of the skimmer opening), the skimmers are unable to draw water efficiently. Instead, they begin to suck in a significant amount of extra air.
  • This ingested air then enters the entire filtration system, traveling through the pump, filter, and other equipment. Under the pressure of the pump, this air is subsequently forced out and bursts through the return jets, creating the visible stream of bubbles you observe. This process can also lead to your pool pump struggling or even losing its prime.

How Air Enters the Filtration System

The journey of air from the pool surface to the return jets involves several key stages:

1. Skimmer Suction: When the water level is too low, the skimmers—designed to pull water and debris from the surface—start to pull in air along with the diminished water flow. You might hear a gurgling sound from the skimmer.
2. Pump Intake: This air is then drawn into the pool pump, which is the heart of the circulation system. Air in the pump can reduce its efficiency and potentially cause damage if not addressed.
3. System Passage: The air continues its journey through the filter (sand, cartridge, or DE), heater, and any other components in the plumbing line.
4. Return Jet Expulsion: Finally, the pressurized air is pushed out of the system through the return jets, creating a constant flow of bubbles back into the pool.

Practical Solutions & Troubleshooting

Addressing bubbles from your return jets often involves simple and effective solutions:

• Check and Adjust Water Level:

  • Ensure your pool's water level is maintained at the recommended height, usually around the middle of the skimmer opening. This allows the skimmers to operate efficiently without drawing in air.
  • Solution: If the water level is low, add water to your pool using a garden hose until it reaches the appropriate level. This is often the quickest fix.

• Inspect for Other Suction-Side Air Leaks:

  • While low water level is the primary culprit, other leaks on the suction side of your pool's plumbing (before the pump) can also draw in air. These might include:
    • A loose or damaged pump lid O-ring.
    • Cracks in the pump housing or strainer basket.
    • Loose fittings or connections at the pump, valves, or other plumbing components.
    • Leaking drain plugs on the pump or filter.

The table below summarizes common issues and their solutions:

Reference Source: Information regarding the most common cause of bubbles from return jets is based on common pool maintenance insights as of 13-Apr-2024.