What Causes Air Bubbles in Pool Filter Systems and How to Fix the Problem

You’ve come to the right place if you’re asking: What causes air bubbles to appear in the pool filter system? A few bubbles are normal, especially when you first start the pump. And if the bubbles disappear after a minute or so, there’s usually nothing to worry about. The real problem starts when you see a constant stream of bubbles and when the pump basket doesn’t fully fill with water while the system is running. That usually means air is getting into your pool’s filter system somewhere it shouldn’t.

When air gets into the system, your filtration becomes less effective, making your pool prone to cloudy water or even algae over time. And if there isn’t enough water flowing through the pump (because air is disrupting it), the pump doesn’t stay cool. It can run dry, overheat, and eventually burn out — which is a much bigger, more expensive problem than just dirty water.

So what causes air bubbles to appear in the pool filter system? Here are some of the most common reasons and how you can fix them:

Excess air in the pump and filter

If you see bubbles in your pool, it usually means that air is being pulled into the system on the suction side of the pump. This commonly happens for a few reasons:

• Your pool’s water level is too low
• The strainer pot lid is not tight
• The O-ring on the lid is worn, loose, or missing
• The union between the pump and valves is not tight
• The O-ring in the union is worn or loose, or even missing

In many cases, you can solve the problem by replacing a worn O-ring or tightening the fittings.

Low water levels

Start by checking your pool’s water level and comparing it to the skimmer opening. If the water is too low, the skimmer will pull in air along with the water and send it straight into the pump and filter system.

Ideally, you should keep the water level about halfway to three-quarters up the skimmer opening to prevent air from entering the system.

Loose strainer lid

Make sure your strainer pot lid is closed tightly. Otherwise, it will keep pulling air into the pump.

Also, inspect the O-ring under the lid to ensure that it’s in good condition and properly sealed. You should also make sure that it’s free from dirt or debris that could prevent a tight seal.

Loose valves and other fittings

If you check the union fitting between the pump and the suction-side valves, you might notice an air leak when the O-ring inside is loose or not in great shape. In that case, you need to tighten the union and make sure the flange sits flush against the back of the nut. If it doesn’t, dirt or debris may be preventing a proper seal, so you need to clean the area and reseat the fitting.

Need new parts?

Did you find problems that need replacement parts? You can always get them from All Pool Filters 4 Less. Order today so your new pump or O-ring can be shipped on the same day or the next day. If you can’t find what you need, text them at 954-558-0584.

About All Pool Filters 4 Less

All Pool Filters 4 Less is an online retailer providing affordable, high-quality pool filtration products and replacement cartridges for residential pool owners. Focused on value, performance, and customer support, the company helps do-it-yourself pool owners maintain clean, healthy water without premium-priced OEM parts.