My buddy Jason used a 50 gallon Rubbermaid tub from his garage. He hooked up a cheap fountain pump from Amazon with some old garden hose for the inlet and outlet. The real hack was using a zip-tied window screen over the drain hole to keep the test fish from getting sucked in. Looked janky as hell but it ran for a full month without leaking.

Ugh, does your boss bring a clipboard? Mine used to do that and I'd get so nervous I'd immediately drop whatever I was holding. It was like a weird superpower he had to make me instantly worse at my job.