Newbie with a 90 gal salt water tank

[dualist]

Hey folks

I am very new to this hobby and am very excited about totally emerging myself in it. I am a diving instructor and have taken some pretty awesome photos of fish in the wild so I am totally hyped and I purchased a 90 gal salt water tank complete with fish and all.... move went awesome.... water was pretty clear that night..... was extremely clear next morn.... fish all survived .... everything went great.... very happy.

Now a few days later... water tests all good..... things are fantastic..mclovin it. Figured hey I need some color in this tank .... went to fish store.... bought clown for single already in tank ... and marine betta..... awesome both are doing well....

The purple long tipped anename I bought didn't fair as well as I figured it was doing well but it made its way into my power head with devastating results. I was not told to shut off the powerhead .... damn..... never knew I would feel so bad loosing something like that but I do..... so that so far is the only loss thus far... expensive lesson to learn... but must move on.

My Question is I have a draining system that flows into the overflow and into the drainag pipe...... this can be adjusted up and down.... it then flows into the sump tank over live rock..... over the divider and into the part with the skimmer.... it then flows through filters into the last part of the sump.... where it then gets pumped back through the return line and back into the main tank via a hose with a slit and shoots diferent directions.

All is good except this thing will bubble and burp constantly .... was quiet the first few days and now sounds like me after a huge stake and lobster diner.... what can I do to stop the gurgling and burping.... we had to close the bedroom doors last night and the system is actually downstairs..... I can see this drivin me crazy.... please help.....