Hotel pools, park district lap lanes and pool tables all bid against you
The single word at the center of your account is one of the most ambiguous terms in local search, and the ambiguity is expensive.
Broad match on anything containing pool will find people looking for a hotel with a pool downtown, a Chicago Park District facility, open swim hours, swimming lessons for a six year old, a pool table for a basement rec room, and a job.
Start narrow. Exact and phrase match on the terms that describe work you sell, a shared negative list at account level, and a search terms report read every week during season rather than every quarter.
Build the negative list around the categories, not one word at a time: public and municipal facilities, hotels and gyms, lessons and swim teams, billiards, above ground kits and big box retailers, DIY and used equipment, and employment. If you do not sell weekly service, openings and closings, exclude those too or they will consume the build budget.
Add the location noise. Searches naming a park, a beach, a hotel brand or a fieldhouse are not your buyer, and they arrive constantly in a metro with this much public swimming.