Aquaponic Gardening

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Hello Aquaponic World,

I hope someone might take a moment and remind me why I'm doing this....

I have now had plants growing since last October in the the AP system and the volunteers growing in the yard are doing better than my AP plants. I am about 25 fish away from going Hydroponic... Here's why.

Last October I built the system.  Since then I have had 35-40 large (4-8") goldfish in the system.  Not a single dead fish.  Not much growth.   

250 Gal IBC (Fish tank)

4'x16'x10" gravel grow bed

4'x8'x8" DWC

60 +/- sump

32- 4 gal Dutch buckets

Water from well ph 6   correction PH is 7

System water  ammonia, nitrates, nitrites, 0.0  & PH sits around 8.0

Lots of aquatic snails

8-10 baby goldfish now 2" :)

Growth has always been super slow.  

Kale and mint doing great.

Lettuce/spinach/ bitter and slow growing.

health lettuce started in grow cubes declines in DWC

Conclusion was not enough waste (nutrition) in system.  
Bought 100 Channel Cat and replaced goldfish with cats.  

Day one hour one 15 dead

Day 2 15 more dead

on day 7 now.  Down to less than 35 fish.  

Next purchase at this point is going to be a sack of fertilizer and some beer batter to cook the last fish and give up on the AQUAPONICs.

I had no idea there would be so much information out there yet no one able to help.  Been to every greenhouse "Garden" Supplier around.  Even went to the local bait and tackle shop to talk fish yesterday.  

I would love some assistance.

Thanks guys

I have pictures of my system and plants on my page.


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I split my dutch buckets off of the AP system and switched to Hydro.  Growth has been incredible.  

Of the 100 =/- catfish, All but one died.  Every gold fish in the system was fine.  Go figure...

So last weekend I converted the entire system over to Hydro.  Built a little fish tank/planter setup to keep the goldfish in and I have to say, I wish I had done this 8 months ago.  The growth is incredible.  

The lettuce that was bitter is getting better by the day.  

Mint is loosing it's mind.  

DWC lettuce is growing for the first time yet.  

I still love the concept of AP, but honestly, with no support, spotty information and no success.  I'm done with that for a while.  Will post some pictures of the growth in a week or two.

I still don't understand how a site this big has no moderator support.  Very sad.

Probably why big producers go hydroponics. You can add more nutrients.

Enjoy the produce.

Looks like your biggest issue is pH.  I suspect your true pH from your well water is up in the 8s.  Good luck with hydro! You will need to correct that pH in hydro as well - it will need to be even lower than in aquaponics...

My PH from my well is 7.0

I have had explosive growth since I began supplementing the system with fertilizer.  Haven't changed the ph a bit.  Just not enough fish for the system.  

I would love to develop a means of keeping it organic, but doesn't look like it is reasonable.   

Oh sorry - I must have misread your first post.  I thought you said the pH from your well water was 6 but that your system water sat at pH of 8.   A pH of 8 will inhibit most nutrient uptake by the plants.  Most hydro system try to maintain their pH from 5.5-6.5.  If it's at 7, then it would explain your great growth!

If well water PH is 7 then how did your system water go from 6 to 8 or 7 to 8 (you wrote it both ways)?  My answer is, it didn't.  PH in aquaponics goes down, not up.  

Nitrite spike probably killed your fish - goldfish are much more tolerant than catfish.  

You are probably doing something wrong with your testing.  All 0 is rare.  

Thanks George.  I wrote 6 in error the first time.  My well water tests at 7.  My system sits at around 8-8.2

Nitrites were tested multiple times. unless my kit is bad that isn't the problem, but thanks for the definitive "assumption".

I have over 64 cu ft of grow bed filter material.  Don't think i had a nitrite spike from 50- 5" fish.  Not to mention it would have leveled off and catfish would have stopped dying after system leveled off.  

Only logical answer is the fish were not healthy when I received them.

Hello StevedNETN,

I'm sorry to hear you haven't been having the best of luck so far with your aquaponic endeavors. I'm also very surprised that nobody from this website has been able to provide any insightful information. That does not happen very often. I hate to hear that someone gets discouraged from aquaponics and gives it up, especially for conventional hydro :( Given your current situation I know it's going to be hard to believe that aquaponics works, but I can say with 100% certainty, it does, and it works very well. 

After reading everything that you have posted so far, I have a few questions that might help me figure out what's going on in your system. They are as follows:

1. What kind of test kit are you using? The fact that you have no form of N registering on your test is quite strange given your fish biomass.

2. How often are you feeding your fish and what kind of feed are you feeding them. (protein % in the feed would be useful too)

3. What kind of plant load do you currently have in your system?

4. Are you supplementing any nutrients in the system? 

Answering those questions will provide a good start to solving this conundrum. I could make a few assumptions as to why you have been experiencing poor growth and you had your catfish die off. First and foremost is your pH. Eddie had it right in saying that you could be experiencing nutrient lockout due to a high pH. Certain plant essential elements are not going to be available to the plants if the pH is too acidic or too alkaline. In your case, the water is very alkaline. Once you get above 8 the main nutrient problems you will see is Nitrogen, Phosphorus and Iron deficiency. The first 2 are of the 3 Primary macro nutrients needed for plant growth (very important). As for your catfish, the pH could have also been the culprit. It is very unlikely that the water that the catfish were transported in had a pH of 8.0. If they were not slowly acclimated to the alkaline water conditions in your system, the shock alone could have killed them. 


One more thing about the pH that isn't making any sense; your pH should not be dropping in the properly functioning aquaponic system. Without getting too deep on this first post, the process of converting the ammonia (NH4) produced by the fish is an acidic process. Meaning that over time in your aquaponic system, the pH will slowly begin to drop. The fact that your pH is increasing from the its starting point when it enters the system can mean a couple things; you have anaerobic  / anoxic zones in your system. This is fairly common in the media bed portion if you have too heavy of a fish effluent load. Another possibility is that the media you are using in the media bed is causing the pH to increase. This can happen if you are using a gravel with a high concentration of lime stone in it.

Hope this helps! I'm looking forward to hearing back from you so we can get this problem taken care of and you can go back to enjoying all of the benefits of growing aquaponically.



Hi Benjamin,

Thanks for the thoughtful reply.

I have an API test kit. Has shown to be reliable so far.    You mention fish biomass. I can't seem to get a straight answer on fish quantity.  Look at my page and you will see my system isn't small.  64 Cu Ft of media is bigger than nearly any system I have seen.  600 gal of water in system and 40 +/- goldfish 4-7" log isn't tiny, but seems to be nowhere near enough.  

The catfish died over more than a 2 week period.

15 were dead in the bag from the stocker.

15 or so the the next morning.  most of them jumped out and died.

then 3-5 per day for the next two weeks.

I killed the last one because I got tired of waiting for him to die.

All the while there were 18 goldfish in the system with them.  Not one of them died.

Shock doesn't seem to make much sense, and a spike of any type wouldn't make much sense either.

Feeding them Purina, it's the only product available near me.  (feed maybe 1 oz a day) not really aggressive eaters.  

Plant load:  I have 45- 3 gal dutch buckets planted and 4x16' grow bed with lettuce and spinach and mint and kale.

Can't find any supplements that seem cost effective.  

Have done compost tea.

I have worms in the system doing very well.  

Had aquatic snails very healthy and reproducing.  (they like to ride in the irrigation system)

I have tested my gravel, and it doesn't appear to be highly alkaline.  It might be slightly.  Hard to tell.  

The fact that the nitrification process isn't driving the ph down tells me I need more ammonia = (MORE FISH)  well more fish died.  

Plant growth is terrible, look at my pictures on my page.

Since removing fish and switching to fertilizer the production has gone insane.  

My Conclusion is for a system as large as mine I need more fish.  If the rule of thumb is 1# of fish per gallon of bed than I need 64 +/-# of fish.  that is probably 10x what I have had at any given time.  In order to do this I would need a substantially larger fish tank and I don't see the viability in this.

My second conclusion is (If you are a fish producer who wants to filter the water than this is a great way to do it..  If you want fresh produce, I have a family of 6... This isn't realistic.)

How large is your system?  What is your ratio of fish tank size to Grow bed & # of fish?



I have hit the site you recommend, bit I don't see what it is. What are they doing that is different than what is being done on standard systems

Not a whole lot - iAVS tend to rear their head on these forums every once in a while.  They were originally used in some of the first early trials of aquaponics.    Regardless of the media you grow in, the challenges will still be the same - managing pH, feed rates, balancing nitrification and supplementation, fish health, plant health, etc.

Ok, Sorry I it not .info.   

So basically it's an ebb and flow system with sand.  It doesn't change the fact that there is a determinate quantity of waste needed to sustain a specific volume of growth.  No matter how you create the two systems (FISH) (PLANTS) one can't exceed the other.  So in my situation with a 20x32 greenhouse and currently less than 30% of it utilized.  I would need a swimming pool size fish tank to keep enough fish to carry that load.  So far I can't find anyone out there doing AP exclusively with a volume of production equal to what I seek.  If I'm missing something, please show me what.  Supplementation would be a great idea, but the products that are fish safe are insainly expensive.  I will update my pictures of the system last night.  take a look

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