Smelly tank

[Coralgurl]

So I have noticed over the last while my house is starting to smell like a fish tank. We just got home from dinner and it is really noticeable. I just cleaned out the skimmer cup last night so it's not that. I've got a lot of detritus on my sand that is now turning red, so hello cyano....tank transfer took place at the beginning of March. I added a sand starfish last night as well but haven't seen him since he went in. I did a water change last weekend and tried to get out as much crap out of the sump as I could, but my vacuum kept clogging up (it attaches to the sink and sucks). Have water ready for salt for a large water change this weekend. What am I doing wrong?