Aquaponic Gardening

A Community and Forum For Aquaponic Gardeners

So I've read it over and over and experienced it myself: small aquaponics systems are unstable.

Below a certain size (200 gallons?) things change fast and your system can crash in a single weekend.

The question is why?

If I have a 200 gallon setup with (20) 2 lb fish, why wouldn't it be just as stable as a 20 gallon system with (20) 2 oz fish?  

I know it's not, but why not? 

Views: 594

Reply to This

Replies to This Discussion

We're all amateur experts LOL. Something has to change the water. The water doesn't just change on it's own. The biggest variable I think are the fish. How much do they weigh, how much do they eat, how much do they poop? Everything else changes based on the fish. I was watching a Bright Agrotech video recently and Nate said "it's much easier to grow vegetables in hydroponics than aquaponics because of the fish variable because everything has to be worked around the fish health".

You know, the thing this doesn't explain is what happened with my 15 gallon system.  I had 100 tilapia fry (2" or so).  The water chemistry was pretty stable.  I had a small amount of ammonia, and nitrates but not much.  However, when I was gone overnight (i.e. didn't add any feed) one night, every single one of them died.  I have a similar stocking density in my 450 gallon system and have never had anything like this happen.

100 fish in 15 gallons is pretty dense stocking. Fish excrete ammonia from their gills regardless of being fed and ammonia is more toxic at higher temperatures and higher PH. Even tiny amounts of ammonia can be toxic in certain conditions. Perhaps you were in the red zone with a slightly elevated PH and it got warm in the room. 15 Gallons will heat up much faster than 450 gallons.

Originally I had 800 tilapia fry in a 45 gallon aquarium ( thought there only about 300 until I counted) They grew there to about an inch before I moved them to an IBC. I had a continuous ammonia problem no matter how little I fed them even with constant water changes but none of them died to my knowledge. Right now I have 14 3-4" tilapia in that tank and the PH hovers around 4 and the ammonia/ammonium is 2-4, deadly in everyone's book. Still no losses. Yesterday I finally put a teaspoon of Calcium Carbonate in the tank and today the pH is 6.9 and ammonia is .5. Hopefully those #s will hold.

Short story long, over the past 6 months I've done all the wrong things with no fish losses (knock on wood) so I have to believe something drastic had to happen to your fish. Oxygen depletion or as Jonathan stated a sudden build up of ammonia. The only thing I can add is that I believe my fish survived the high ammonia readings because of the extremely low pH. Below 7ish pH ammonia becomes ammonium and fish can process it without damage. Try to add a buffer of some kind to slow rapid changes to your water readings. I'll let you know how my addition works.

I think that would be safe to say; at least, that's how I've always understood it. But I could be missing something as well.

Jeremiah Robinson said:

I think I hear what you're saying.

Basically if I did everything with measuring spoons and droppers the systems should be just as stable no matter the size.  Is that right, do you think?

You also could have had an oxygen problem. That's a fairly heavy stocking density, and if it's not properly aerated things could happen. Especially as it starts to get warmer outside. Higher temp water holds less oxygen.

Jeremiah Robinson said:

You know, the thing this doesn't explain is what happened with my 15 gallon system.  I had 100 tilapia fry (2" or so).  The water chemistry was pretty stable.  I had a small amount of ammonia, and nitrates but not much.  However, when I was gone overnight (i.e. didn't add any feed) one night, every single one of them died.  I have a similar stocking density in my 450 gallon system and have never had anything like this happen.

Hi Jeremiah,

I can't say I agree with your statement. I have run 100 gallon systems and have no problems. Provided you have at least a 12" deep media growbed and maintaining quality and consistent amount of fish feed.

When water loses its hardness ph  changes fast ... big or small system ...got crushed lime stone ready when it happens. Will add or take if needed to change ph ...

Reply to Discussion

RSS

© 2022   Created by Sylvia Bernstein.   Powered by

Badges  |  Report an Issue  |  Terms of Service