Skimmer Equipment /
What Are the Two Holes in a Pool Skimmer?
A pool skimmer with two holes may serve different plumbing functions, but the exact setup varies by model. Identify it safely with the manual before touching anything.
Archive date: this article was written for PoolSkimmer on Oct 7, 2026 and given the earlier archive date of Oct 8, 2025 so the blog reads as an organized archive. It was not published on that date.
In brief You will often find a pool skimmer with two holes to accommodate separate water paths, though what they are for is dictated by the particular model and how the plumbing is laid out. One side might feed the pump suction line, the other could be an equalizer or drain. It is not something to put stock in based on looks alone.
Your best course of action is to consult the skimmer manual, the pool diagram or any labels at the equipment pad before you do anything.
The reason for the two holes Plumbing is not uniform from one pool to the next, so it would be a mistake to think all skimmers operate identically. The dual openings are there because the manufacturer and installer set them up that way for your system. They may be used to circulate water, handle surface debris or ensure flow when the level is low.
In some cases you have:
- a direct path to the pump
- an equalizer or backup
- a tie-in to the spa or pool design
What constitutes a second hole on your pool may have no such meaning on a neighbor’s.
A safe way to inspect Any work on the skimmer basket should be preceded by turning off the pump at the controls to eliminate suction risk and safeguard the equipment.
Once the pump is down:
- take off the lid
- clear the basket of any debris
- check the body of the skimmer for any molded labels or markings and cross reference with the manual
- put on gloves if the matter in the basket is sharp or unclean
Under no circumstances should one reach into a live suction or put an object in either hole while the pump is running.
What to steer clear of The pair of holes at the bottom of the skimmer can be an invitation to experiment. Do not fall into the trap of trial and error. Some errors to avoid are plugging an opening that seems to be of no use, using a rag as a stopper, or assuming the extra hole is invariably a drain. Restarting the pool without making sure the lid and basket are in place is another common misstep. Mess with the wrong port and you risk straining the pump, hampering circulation or creating a hazard.
Time to get help There is no harm in calling a qualified professional when:
- the setup does not correspond to the manual
- you are unsure of the function of each hole
- you detect air in the lines, odd noises from the pump or a loss of prime
- the skimmer lid is damaged or fails to seal
- there is an electrical fault or tripped breaker
If there is an electrical problem or the water is not circulating properly, do not swim.