Air bubbles in pools can come from several sources. One of the first things to check is whether there is air inside the filter basket of you pool pump. If so, the leak is coming from the suction side of your pool plumbing. There may be an air leak at a joint in the plumbing itself, or the air may be coming from another source like a pool vacuum hose. One of the most common air intrusion sources on the suction side of pool plumbing is very simple to diagnose and resolve. Your pool may simply be low on water!
When the water level of your pool goes down due to evaporation, splashing, or water leaks in plumbing, your skimmer basket may start to suck air into the circulation system. This may result in continuous bubbles in the pool as a vortex is formed in the round skimmer inlet. It can also be intermittent as the skimmer door bobs up and down or gets stuck in the closed position. Either way, adding water to the pool up to the proper level should alleviate this issue.
One way to diagnose air in the skimmer is to shut off your skimmer suction line and draw all water from the main drain(s). If the bubbles go away, you have air getting into the skimmer, and a low pool level is your likely issue.
This time of year in Southwest Florida is the most common time people run into this issue. Evaporation rates are relatively high due to rising ambient temperatures, warming pools, and steady winds. Solar and traditionally heated pools have even higher evaporation rates. You will need to add a significant volume of water to your pool in the spring until the regular afternoon rains come. I’m running my hose about 30-60 minutes per week this time of year.
A pool cover will substantially reduce water usage, but I’ve found that this is the time people are enjoying their pool the most, and the hassle of using a pool cover is often undesirable. An automatic fill mechanism can be added by your pool professional, but these systems can be wasteful and may mask leaks causing an unexpectedly high water bill. There is a trade-off for convenience.