If it smelled, it was probably a fungus, but could haven been a bacteria too. I don't think you have any plants in the system yet right? If not, I would take apart the system and wash it all with soapy water. Rinse it off, then put some bleach water in a spray bottle, and spray it down with the bleach water a few times. And after taking the
pump apart and washing it too, soak the pump in H202. Then after cleaning and sanitizing everything, run some plain water in it with a good amount H2O2 for at least 24 hours (like whole 32 oz bottle with 5 gallons of water). Once you get a fungus in the system, it's very difficult to get rid of. You pretty much just have to take it completely apart, then clean and sanitize it all. Even then just one spore can start it all back up again. If it was bacteria and there was any areas that were missed and they survived, they'll multiply quickly too.