Help Beginning of old tank syndrome?

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vinzphua

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My tank water smells of fish poop. Not super strong, but it's there in the background when I'm cleaning the tank. Been many months now. With or without algae outbreaks, its been consistent.

I suspect old tank syndrome is beginning.

I have some plans in mind, but before I go down this rabbit hole, I'll like to do a sanity check.

pH is around 6.9 to 7 without CO2.
I do regularly weekly water changes, about 35% or so. Can't do more because the arowana gets jumpy when the water gets too low. Only skip once in a few months if a week is particularly busy.

The tank is 10+ years old, substrate has never been changed. Vac is irregular, maybe once a few months. I dose Microbe Lift Special Blend and Microbe Lift Substrate Cleaner to help stretch the substrate vac interval. There is an area that I almost never vac because I never replant that area. Its covered with Red Tiger Waterlilies.

The bio-media is also many years old, but not 10, maybe 5 years? Quite clean as far as I can tell (sump). Ever since I started dosing Special Blend, there's very little mulm stuck in between.

The filter pad is rinsed weekly and replaced monthly.

So far the fishes are fine. I don't see any abnormal behaviour.

I am guessing its the substrate (primary suspect) and/or the bio-media (secondary suspect).

So, what do you all think? Old tank syndrome? Or is it something else? Any experience, advice or suggestions about what to do? As mentioned, I do have some plans in mind, but would like to see what you all say first.

Thank you.
 
What are your nitrates, and how much N are you dosing? If nitrates haven't accumulated to sky high levels in such a long period of time, I think that is good evidence that maintenance has been sufficient and would rule out old tank syndrome. It sounds like your tank is getting regular maintenance, but I'm not familiar with keeping arowana or having a tank large enough to keep them, so I don't have a sense if what you've been doing is *enough* for such a specialized monster fish. But age of the substrate and biomedia alone isn't going to cause old tank syndrome.

The only issue you are having is you think the water smells like fish poop? Could you describe that smell? I have no idea what fish poop smells like exactly, but could be other things causing a bad smell. Cyanobacteria, sulfides from the substrate, dampness from a slow leak somewhere...
 
ElleDee said:
What are your nitrates, and how much N are you dosing? If nitrates haven't accumulated to sky high levels in such a long period of time, I think that is good evidence that maintenance has been sufficient and would rule out old tank syndrome. It sounds like your tank is getting regular maintenance, but I'm not familiar with keeping arowana or having a tank large enough to keep them, so I don't have a sense if what you've been doing is *enough* for such a specialized monster fish. But age of the substrate and biomedia alone isn't going to cause old tank syndrome.

The only issue you are having is you think the water smells like fish poop? Could you describe that smell? I have no idea what fish poop smells like exactly, but could be other things causing a bad smell. Cyanobacteria, sulfides from the substrate, dampness from a slow leak somewhere...
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Nitrates are fine. In fact, had to boost nitrate on top of APT Complete to keep the plants happy sometime back.

Definitely not BGA, nor sulfides, nor dampness. I know those smells.

Not sure how to describe it. Could say it's sort of a fishy smell that some older, less well maintained LFS have. Not a rotting fish smell. Not very nasty. Just mildly unpleasant.
*Ci* said:
What, exactly, is old tank syndrome?
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18.5. Old Tank Syndrome

Old tank syndrome is when an aquarium has low pH, high ammonia and very high nitrates,
aquariumscience.org aquariumscience.org

Admittedly, my tank currently doesn't fit most of the description. But my gut suspect it might be beginning.
 
Is it possible that something is wrong with your arrowana? Like it might be a change in the odour of the actual feces? This is certainly true for mammals, indicating a digestive issue or sign of disease.
Have you made any changes in its diet?
 
*Ci* said:
Is it possible that something is wrong with your arrowana? Like it might be a change in the odour of the actual feces? This is certainly true for mammals, indicating a digestive issue or sign of disease.
Have you made any changes in its diet?
Click to expand...
Thanks. No change in either.
 
Naturescapes_Rocco said:
Is it only present when you're doing water changes?
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It's there all the time. It does not permeate the room, but if I'm doing maintenance, and my face is right up to the water, I might smell it. Usually, I'll smell it on plants that I just pulled out.
 
I would siphon/turkey baste those areas that have been neglected, clean the filter, and do a big water change (maybe a couple).
 
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