Had a similar problem on a brand new 190 bay boat with the exact same aerator pump. It ended up being a small crack in the pump cartridge. I figured it should have warranty so I emailed Rule customer service which took about two seconds, below is the response I received the following day! Excellent customer service.
Hi Brad:
Thanks for your note. And, yes, we stand behind our product. I will get another cartridge out to you. It should take about two weeks. Please call me if you have other questions or concerns.
Best regards,
Andrew ######
ITT Rule