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Will be building an indoor system with additional airstone but I was wondering if the fish  and plants have a limit as to how much air (DO) should be in their water? Is there such a thing as too much?

 

This will be a small system with 55 gallons of water max and a 2x4 growbed. Still deciding on whether to go with tilapia, koi or goldfish but limiting them to under 6 pounds at maturity.

 

Thanks,

Sue

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Sue,

Coming from the Aquaculture side yes, coming from Aquaponics I have been told no.  On the hatchery side DO was great until a tank was not cleaned properly, removal of fish waste and food.  Excessive DO caused excess nutrients to develop in the tanks and algae blooms would happen and then chemistry went to heck!  That was bad for the fish.  But in AP all those nutrients should be making it to your beds so the issue is typically nullified.  I have a 20 gallon tank and I have made a habit of hitting it with a quick vacuum on the bottom to pick up anything not pulled by the pump, then I just dump that water into the grow bed.  I have goldfish they are giant poop machines sometimes the waste gets stuck under the pump, air stone or in a far corner, but nothing is wasted.

In answer to your question -NO. Water will only absorb so much oxygen and no more, how much oxygen is determined by the water temperature. Cooler water will contain more oxygen, water movement will ensure good distribution.   

Yet another argument for the pump being in a "fresh water" sump. I can't stress that enough but I realize that not everyone can dig a big hole in the floor

I am reminded here of a thread on another forum that stated (at least with O2 hungry Trout) "You know you have too much air when it blows the fish out onto the floor"

John Cubit said:

Sue,

Coming from the Aquaculture side yes, coming from Aquaponics I have been told no.  On the hatchery side DO was great until a tank was not cleaned properly, removal of fish waste and food.  Excessive DO caused excess nutrients to develop in the tanks and algae blooms would happen and then chemistry went to heck!  That was bad for the fish.  But in AP all those nutrients should be making it to your beds so the issue is typically nullified.  I have a 20 gallon tank and I have made a habit of hitting it with a quick vacuum on the bottom to pick up anything not pulled by the pump, then I just dump that water into the grow bed.  I have goldfish they are giant poop machines sometimes the waste gets stuck under the pump, air stone or in a far corner, but nothing is wasted.

You can have problems if you "super-saturate" the water with any gas.   Gas Supersaturation

The "problem" with aeration is that "air" isn't oxygen... or even mostly oxygen; so it's easy to accidentally supersaturate your water with nitrogen or carbon dioxide while you're trying to increase the dissolved oxygen levels.

I read where somebody was introducing air into the inlet of their water pump; which is definitely dangerous.  If you supersaturate the water with nitrogen from the air, the fish can get "the bends" just like deep divers do if they don't decompress.

Aquatic-Eco TechTalk : "The effect of excessive supersaturation on fish has been well documented and has caused massive fish kills."

Good stuff David. I for one have learned something. Thank You. Ultrasonic nozzle I got out the other day is probably not worth testing then. Back when we used them we didn't have to worry about fish, only bacteria.

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