You can try to claim fraud or nuisance as to the pool hours. However, before you do that, speak to the management and see if they will let you out of the lease or find a better way to enforce the curfew.
Fraud or nuisance is hard to prove and you could end up being found in breach of lease and having to pay back rent.
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You have the right to "quiet enjoyment" of your tenancy, which doesn't necesarrily refer to noise, but in this case it does. Does your lease address "quiet enjoyment"?
You also have the right to have management enforce its stated rules, including the curfew on the pool use. Have you put your complaints to management in writing? Have you asked for management to issues fines to those violating the curfew?
You may want to hire a lawyer to put your rights under the lease and these violations in writing to management.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.