# Aquarium knocking sound



## zergling (May 16, 2007)

Maybe you have a mantis shrimp? Oh wait, that's saltwater :hihi:

Do you have a canister filter? Check the pipes to see if they're tapping the glass. I get this a lot as whenever I adjust my outflow pipe, as it is right next to the front glass.


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## MuddyWishkah (Oct 22, 2009)

I had this too. My heater would knock against the side of my tank when the suction cups would loosen.


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## Bandit1200 (Dec 11, 2010)

My oscar used to knock stuff against the side of his tank when he was hungry. Eventually I had to keep him in a bare tank, not even a heater as he had learned how to grab it in his mouth at the bottom and swim backwards with it as far as he could to let it go and whack into the inside of the tank. It was kind of funny at first, sort of like when the baby figures out how to change the channel on the tv... amusing for about 3 seconds.


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## Aftica (Nov 26, 2003)

zergling said:


> Maybe you have a mantis shrimp? Oh wait, that's saltwater.


ROFLMAO - funny that was my first thought too.....





zergling said:


> Do you have a canister filter? Check the pipes to see if they're tapping the glass. I get this a lot as whenever I adjust my outflow pipe, as it is right next to the front glass.


Perhaps a canister that occasionally gets a little bit air locked? Got an air stone near the inlet to the filter? Or feed co2 into the inlet side of the canister?


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## Big O (Jun 28, 2011)

Do you have loaches? My loach's make tapping and snapping noises all the time. I also had a* Raphael catfish that made some strange noises.
*


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## Tenor1 (Jan 15, 2012)

This is such a funny thread of experiences, I LOVE that oscar story. It was a heater in my tank that would give a knock and I just secured it better. It's usually some type of hardware not secure in the tank, unless you have an oscar lol. Remember that suction cups harden and can cause this problem.


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## NWA-Planted (Aug 27, 2011)

has to be something loose, I wouldnt think the glass, cause glass giving way is a shearing cracking sound... not mention if you heard a pop that would probably the silicone letting go and in both cases you would know!!!


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## Zefrik (Oct 23, 2011)

I have two pistol shrimp in my saltwater and at night I hear loud cracking sounds. Although this has nothing to do with your problem. I don't know what else it could be.


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## Cp1251 (Jan 4, 2012)

MuddyWishkah said:


> I had this too. My heater would knock against the side of my tank when the suction cups would loosen.


So after another month of hearing this sound I finally got agitated. I started removing pieces to my quarantine tank. 

First I removed my co2 pump, then one canister filter. THEN I removed the heater and put it in the other tank. The other tank started making the same sound. The heater was doing just as you said.

Thanks muddy wishkah


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