Does Your Marine Aquarium Pass the Smell Test?

Your senses play as important a role in maintaining your aquarium as test kits and monitoring devices

Your senses play as important a role in maintaining your aquarium as test kits and monitoring devices

We marine aquarists depend heavily on store-bought test kits and devices for monitoring water quality and parameters (like the FishBit monitor we discussed here recently), but we’re actually born with some of the best tools available for figuring out what’s going on with our tanks—our innate human senses.

With the possible exception of taste (I’d recommend observing the general admonition that you shouldn’t put your tongue on anything related to your aquarium), our senses can tell us quite a bit about the health and well-being of our systems—if we pay them heed, that is. Here are some examples of how:


Obviously, our eyes give us the most comprehensive information about our tanks, so we’ll start there. They reassure us that our livestock is healthy and behaving normally, getting enough to eat, and interacting peacefully; that there’s ample water movement in the system (evidenced by swaying corals, particulates kept in suspension, etc.); that the lighting system is fully functional with no burned out bulbs/tubes/LEDs; and so forth.

But sight isn’t the only sense that’s helpful to the marine aquarium hobbyist. There’s also…


Unusual or louder-than-normal sounds often indicate that something is wrong in an aquarium system. For example, a rattling sound coming from a submersible pump or HOB filter could indicate a broken or cracked impeller. Or, if you hear a loud sucking sound (often combined with the visual symptom of myriad tiny bubble discharging into the tank), your return pump may be sitting high and dry and in imminent danger of burning out.

Though it took me a while to pinpoint the source, I once identified a dangerously malfunctioning heater by a subtle knocking sound that would occur very intermittently. After finally identifying the origin of the sound (and verifying that I wasn’t going crazy after all), I discovered that the heater in question had quite a bit of moisture building up on the inside of the glass casing.

Sound can sometimes even tip us off to the presence of hitchhiking organisms in our tanks, such as pistol shrimp or mantis shrimp, which can make loud snapping, popping, cracking, or clicking sounds when burrowing into rock or dispatching prey with their specialized appendages.


One helpful habit I established long ago is to occasionally run my fingers along any external tubes, pipes, or cords leading to/from my tank as well as the outside seams of the tank itself and the overflow box. In so doing, I hope to detect any minor leaks or drips (evidenced by moisture) before they become major or catastrophic ones.


Sometimes the nose is the first to know when something is amiss with a marine tank. For instance, your system’s water should have, for lack of a better description, a pleasant ocean-like aroma. If your water has an “off” or foul odor, check all your water parameters and make sure you don’t have any deceased specimens in the tank. A nasty rotten-egg smell emanating from the tank could be a significant warning sign, as it could indicate that potentially toxic hydrogen sulfide is being produced in anoxic areas of your system (e.g., in a deep sand bed containing decaying organic matter).

Have you come to your senses?
So, fellow salties, how do you put your senses to the test in maintaining your aquarium system? Let us know in the comment section below.

Photo credit: Dennis

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About Jeff Kurtz

Jeff Kurtz is the Co-founder/Editor of Saltwater Smarts, former Senior Consulting Editor for Tropical Fish Hobbyist Magazine, and the aquarist formerly known as “The Salt Creep.” He has been an aquarium hobbyist for over 30 years and is an avid scuba diver.


  1. Occasionally your tank will have a weird smell that is not a sign of doom if you keep a lot of anemones. They exude an odor which doesn’t exactly smell like Channel #5. It is sort of musky and they don’t do it all the time. Also your corals will sometimes exude an odor. You can tell what that smell is if you run your fingers over an LPS coral, then smell your fingers. Avoid doing this in public.
    But as Jeff said, it should not smell like a moose died in there last Tuesday as that is a sure sign of Doom.

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