Aquaponic Gardening

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I have recently started experiencing an interesting problem with my micro-nutrient balance in the micro system.  Since I started running the system in different configurations in 2008, I have not seen this problem and was wondering if others have experienced the same.  One of the cornerstone assumptions of AP is that if you start off with a GOODquality fish food, you should have all the trace elements needed in the system, barring Molybdenum and Boron.  In terms of fish food in South Africa, it is not all that easy to shop around.  We have one established and one new supplier, and the range of pellets that they do is rather limited.  In the past to date, I have used three different food types in my system, all from the same established manufacturer.  I ran the system from set-up to late 2009 on a high grade koi pellet, as the tilapia feed is only sold in bulk and I was not going to buy a huge amount of food and watch 80% of it spoil.  I had 20 fish! When I moved the system, I bought new tilapia stock (gave the old away when I took the system down) and got a kg of the tilapia food used by the supplier to set them up.  When this ran out, I decided to get a bulk bag of tilapia food from the supplier, but could not get a match to what I was using.  Protein content went up from 35% to 41% (way too high in my opinion) and the pellet was smaller and lighter in colour.  The manufacturer does not print exact nutrient break-downs on the packaging, thus I am in the dark about what I am using.  Since I switched to the current bag, I have seen every type of difficiency except nitrogen and Molybdenum manifest itsself in the system.  At first I was at a bit of a loss, but I have had enough time to run troubleshooting to the point that I want to blame the food.  I do not lime excessively, supplement potassium every now and then, have a 6.5 pH  and the fish are feeding very well.  When I add chelated iron and trace elements, the problems go away.

 

Has anyone else found these problems and what, other than supplementing, has been done to fix the problem?  My options are limited in terms of food source.   

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Hi Kobus.  I have access to high quality feed (made by Kellen Weissenbach in this community) so I'm not seeing any problems, perhaps per your theory...which I agree with, by the way.
As part of my horticulture classes we did soil tests to find out the makeup of the soil. I wonder if the same tests would work with your aquaponics water.

I have a lot of CSMB + Boron laying around. I wonder if it will work . Maybe I will dose a little.

 

I got it from Aquariumfertilizer.com

 

Guaranteed Analysis:

Total magnesium - water soluble chelated magnesium                1.5%

Copper - chelated                                                                    0.1%

Iron - chelated                                                                          7.0%

Manganese - chelated                                                              2.0%

Molybdenum                                                                           0.06%

Zinc - chelated                                                                         0.40%

Boron                                                                                      0.04%

EDTA - minimum content                                                        55%

 

 

I'm of the belief that it is not just the fish feed but also the source water and media that affect the nutrient situation in a system.

 

It seems like a great idea to be able to say the fish feed should be all you even need to add, however, if you are using rain water, you are probably missing out on a host of trace elements that many people probably get from other water sources.

  My well water is full of minerals, especially lime but it's kinda deficient in iron and perhaps some others.  Not all source water is the same so I expect that needs to be taken into account.

 

There are different fish feeds formulated depending on if the fish are in tanks in recirculating culture or if they are in earthen ponds since the earthen ponds provide nutrients that the tanks don't.

 

I personally wouldn't get too upset about having to use the iron and trace elements, ya gotta do what ya gotta do. 

TCLyncx - I would not have had such an issue with needing to supplement a bit of nutrients every now and then, but loosing my cucumber plants completely and having almost all the other plants except the passion fruit look miserable is not cool.  I say this in part because the food is what I would recommend to other people in my area, would be using in commercial trials and am using now curtosy of buying a 25 kg bag of it.  The fish also need those nutrients, so I am wondering how balanced the food is from a fish perspective as well.  In terms of the rain vs other water, I'm stumped for options with one exception.  Municipal sucks and we are severely limited.  One province in the enrite freakin country is still in drought and guess which one that is.  Yeah.  Us!  We cannot drill a well because we are on a protected aquifer, but our farm is close and we have a good borehole there.  If it tests well, then perhaps I can end up swiping "top up" water from there.

 

In terms of testing, you can test water for anything if you specify what you want tested - same with the food.  I just do not see the need for testing the water because the plants show me that they are not happy.  I am going to have the food analysed though under the umbrella of the aquaculture research I am busy with now.

TCLynx said:

I'm of the belief that it is not just the fish feed but also the source water and media that affect the nutrient situation in a system.

 

It seems like a great idea to be able to say the fish feed should be all you even need to add, however, if you are using rain water, you are probably missing out on a host of trace elements that many people probably get from other water sources.

  My well water is full of minerals, especially lime but it's kinda deficient in iron and perhaps some others.  Not all source water is the same so I expect that needs to be taken into account.

 

There are different fish feeds formulated depending on if the fish are in tanks in recirculating culture or if they are in earthen ponds since the earthen ponds provide nutrients that the tanks don't.

 

I personally wouldn't get too upset about having to use the iron and trace elements, ya gotta do what ya gotta do. 

Interested to hear what the analysis of the food will tell.  I hope you can find a better fish food too and I expect you are right that the higher protein isn't as appropriate to your tilapia.

 

Yea, some minimal supplementation of micro/trace elements as well as iron, lime, potassium seems fine to me but it shouldn't have to be extreme.

 

My main comment about the rain water came cause I know some one not to far from me that switched from using well water to using rain water for their system.  They hadn't realized (till after a bit of a pH and buffering disaster) that the rain water was really soft and had no buffering capacity and that in his case adding some different kinds of lime would be necessary to get things back in balance when using rain water for his system.

 

(By the way, I've managed to grow many things very well in aquaponics but I have not yet managed to get any cucumber plants to look happy in aquaponics.  I'm hoping that most of that problem with cucumbers was with my big system and it's high pH so this spring I will try some cucumbers in my 300 gallon system where the pH runs lower.)

We have seen major issues here in my area with people, me included, switching to rain water for swimming pools.  Alkalinity is around 30, while most pools here need to be between 80 and 120.  We have massive algae issues, salt water pool chlorifiers work differently, it is actually quite amazing.  Storing rain water can also have some issues, as does your roof.  My micro system is mostly plastic and pvc, and it settles on 6.5 on rain water, liming included from galvinized iron roof.  The research unit is polycarb, with supplementary water from a tiled roof.  The components are fibreglass, and the pH goes up beyond 8.

 

The cucumbers grew beatifully and the two plants yielded about 10 fruit when all of a sudden, they hit a wall and died, developing fruit and all.  See pic below.  Abiout three weeks after it was taken the cucumbers were done for. 

TCLynx said:

Interested to hear what the analysis of the food will tell.  I hope you can find a better fish food too and I expect you are right that the higher protein isn't as appropriate to your tilapia.

 

Yea, some minimal supplementation of micro/trace elements as well as iron, lime, potassium seems fine to me but it shouldn't have to be extreme.

 

My main comment about the rain water came cause I know some one not to far from me that switched from using well water to using rain water for their system.  They hadn't realized (till after a bit of a pH and buffering disaster) that the rain water was really soft and had no buffering capacity and that in his case adding some different kinds of lime would be necessary to get things back in balance when using rain water for his system.

 

(By the way, I've managed to grow many things very well in aquaponics but I have not yet managed to get any cucumber plants to look happy in aquaponics.  I'm hoping that most of that problem with cucumbers was with my big system and it's high pH so this spring I will try some cucumbers in my 300 gallon system where the pH runs lower.)

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How odd.  Cucumbers in my system rarely ever got more than a couple feet tall, probably iron deficiency early in development doomed mine.

 

99.9% of the cucumbers I've grown over the past three years have been in mushroom compost and they do very well until the caterpillars take over.

 

But bigger vines like that dieing, hum...  I've had that happen to me when vine borers get in near the base, whole plant dead very quickly?

 

Hum, I'm eager to hear how it sorts out cause I have faith that you will figure out some solutions.

First sign of problems were leaves yellowing and falling off - older first.  Then the fruit stopped developing and the new growth tips packed up.  I pruned them to see if they will get a second wind, but no - completely dead.  In the same bed, I have some flat-leaved parsley that seem perfect, and the passion fruit that started slowly but is coming along very nicely now.  Apart from my cucumbers going, the different leaf crops I tried all struggled, and the basil went ugly.  They got pruned and are looking good again.  All new tomatoes and the established strawberries show signs of deficiencies.  Newly established spring onions doing well but the peppers I planted way back are still very small.  A mixed bag of allright and dead with some happy, with no real indicator other than the diet shift.

TCLynx said:

How odd.  Cucumbers in my system rarely ever got more than a couple feet tall, probably iron deficiency early in development doomed mine.

 

99.9% of the cucumbers I've grown over the past three years have been in mushroom compost and they do very well until the caterpillars take over.

 

But bigger vines like that dieing, hum...  I've had that happen to me when vine borers get in near the base, whole plant dead very quickly?

 

Hum, I'm eager to hear how it sorts out cause I have faith that you will figure out some solutions.

And I thought it was just me, something i was doing wrong.Thanks for bringing this up Kobus. Two cucumber plants, got to fruit and started to wither and died. What got me is that they really took off and in just a few weeks started fruit, looked just the picture of health, and within one week, yellowed and died. I've read that they do extremely well in raft and I'll be trying that next for sure. I too switched fish food and noticed about 30%-40% better growth. Trace and macro elements are easy to add as a supplement to any system but I think fish need high quality protein to grow, and as they grow the system will mature.
I see a blog topic coming up.  I don't have an issue with supplementing, but to get back to a system health and commercial system point of view, the feed you pick has to have eveything the fish require at least, and having 10% too much protein and likely a lack in trace elements could influence the health of the fish.  I have not lost any of the tilapia, but if their growth is not optimal and if I am tossing in supplements all the time, my already slim margins will look even worse here in South Africa.

Harold Sukhbir said:
And I thought it was just me, something i was doing wrong.Thanks for bringing this up Kobus. Two cucumber plants, got to fruit and started to wither and died. What got me is that they really took off and in just a few weeks started fruit, looked just the picture of health, and within one week, yellowed and died. I've read that they do extremely well in raft and I'll be trying that next for sure. I too switched fish food and noticed about 30%-40% better growth. Trace and macro elements are easy to add as a supplement to any system but I think fish need high quality protein to grow, and as they grow the system will mature.
Hi Kobus
I use to feed my fish on a 4mm pellet that was developed by the Stellenbosch university.
I had to buy in 25 kg bags + transport....
cost of food was very expensive due to transport
was I using the same brand fish food as you...
francois

Kobus Jooste said:
I see a blog topic coming up.  I don't have an issue with supplementing, but to get back to a system health and commercial system point of view, the feed you pick has to have eveything the fish require at least, and having 10% too much protein and likely a lack in trace elements could influence the health of the fish.  I have not lost any of the tilapia, but if their growth is not optimal and if I am tossing in supplements all the time, my already slim margins will look even worse here in South Africa.

Harold Sukhbir said:
And I thought it was just me, something i was doing wrong.Thanks for bringing this up Kobus. Two cucumber plants, got to fruit and started to wither and died. What got me is that they really took off and in just a few weeks started fruit, looked just the picture of health, and within one week, yellowed and died. I've read that they do extremely well in raft and I'll be trying that next for sure. I too switched fish food and noticed about 30%-40% better growth. Trace and macro elements are easy to add as a supplement to any system but I think fish need high quality protein to grow, and as they grow the system will mature.

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