supersaturation of oxygen

[fishdip22]

So I was reading one of the many books I have on aquariums this book is called (Advanced marine Aquarium techniques) by Jay F. Hemdal and one of the things it talks about is super saturation in the aquarium. My question is what are the odds of a normal home aquarium having to much O2?

[Nano sapiens]

Originally Posted by fishdip22

So I was reading one of the many books I have on aquariums this book is called (Advanced marine Aquarium techniques) by Jay F. Hemdal and one of the things it talks about is super saturation in the aquarium. My question is what are the odds of a normal home aquarium having to much O2?

Unless you are injecting O2...none.

[zachfishman]

It isn't supersaturation of oxygen that is the issue, but rather supersaturation of nitrogen. Both can become supersaturated easily if a pump receives air on the intake side (sump microbubbles, a pin hole leak on the intake, etc.). For larger pumps and systems, this air is then pressurized in the return, forcing air into solution. When that pressure is released (in the display), your fish essentially can get the bends. Just like for scuba divers, excess oxygen isn't an issue as the body utilizes it quickly.

If you have higher head pressure (big pumps, a downstairs filtration room...), making sure no air gets to the intake side of your return pump is very important.

[fishdip22]

Originally Posted by zachfishman

It isn't supersaturation of oxygen that is the issue, but rather supersaturation of nitrogen. Both can become supersaturated easily if a pump receives air on the intake side (sump microbubbles, a pin hole leak on the intake, etc.). For larger pumps and systems, this air is then pressurized in the return, forcing air into solution. When that pressure is released (in the display), your fish essentially can get the bends. Just like for scuba divers, excess oxygen isn't an issue as the body utilizes it quickly.

If you have higher head pressure (big pumps, a downstairs filtration room...), making sure no air gets to the intake side of your return pump is very important.

How would one tell if this was a issue?

[zachfishman]

Originally Posted by fishdip22

How would one tell if this was a issue?

At work it was numerous fish deaths in a particular tank that we couldn't figure out (no obvious disease, no odd water parameters, fish eating fine, etc.). We'd just kept losing apparently healthy fish every 2-3 days for no discernible reason. We only figured it out after bringing in a University of Florida extension service that came and tested our water with a gas saturometer (not a cheap instrument). They were able to measure our saturation (105%) and then confirm a reduction weeks later after we implemented several modifications to the system. Unexplained losses stopped after this, so it was likely the cause.

[fishdip22]

Originally Posted by zachfishman

At work it was numerous fish deaths in a particular tank that we couldn't figure out (no obvious disease, no odd water parameters, fish eating fine, etc.). We'd just kept losing apparently healthy fish every 2-3 days for no discernible reason. We only figured it out after bringing in a University of Florida extension service that came and tested our water with a gas saturometer (not a cheap instrument). They were able to measure our saturation (105%) and then confirm a reduction weeks later after we implemented several modifications to the system. Unexplained losses stopped after this, so it was likely the cause.

Did you guys do (necropsy) on them? if so did the gills look different that you can remember?

[zachfishman]

Originally Posted by fishdip22

Did you guys do (necropsy) on them? if so did the gills look different that you can remember?

We didn't. Pretty much every fish we extracted was significantly decomposed by the time we got to it (this system is one of our remote installations). We had the UF extension perform a few of these as well as some histology when we weren't yet certain what was going on. They found a lot of granulomas in the sampled fish, but while a potential symptom it didn't point specifically to supersaturation.

If you can see gas bubbles in the gill capillaries (and are sure that it wasn't introduced when cutting the gill clip), that is a pretty telling symptom.

[fishdip22]

Originally Posted by zachfishman

We didn't. Pretty much every fish we extracted was significantly decomposed by the time we got to it (this system is one of our remote installations). We had the UF extension perform a few of these as well as some histology when we weren't yet certain what was going on. They found a lot of granulomas in the sampled fish, but while a potential symptom it didn't point specifically to supersaturation.

If you can see gas bubbles in the gill capillaries (and are sure that it wasn't introduced when cutting the gill clip), that is a pretty telling symptom.

Good to know. Thank you for sharing your experience and knowledge with me.