Is it a Urine/Pee smell?
yup.....pee, or dead animal. stand does not even have doors yet.
not too much flow due to small return pump but i thought that was the idea. bigger pump is on the list, right passed mortgage and car payment
this same thing happened to me when I was starting to cycle out my new tank. I had to turn off the powerhead that brings the water to the aquarium, my aquarium started to smell like pee the following morning. I turned the flow back on, poured alot of the sera ammovec biostarter stuff. After 3 days, the water does not have any smell at all! My skimmer pulled out alot of stuff from the water also. My skimmer is skimming from the refugium.