Backyard Aquaponics
A place to discuss aquaponics

Hi Martin,


Great to see there are some fellow South Africans here.

But first of all, Ronmaggi is not a Soutie he is a Yank.

Daardie term kom van die dae toe ons nog onder Britse bewind was en wás gebruik vir ingelse. Een voet in die republiek en die ander op die koningkryk met die totter wat in die see hang en daarvan die term Soutpiel wat toe afgekort is Soutie toe.

I take note of the concern about the media I use but I think I am observing close enough to avoid catastrophy and after all, I have no intention to push the system early on for the absolute maximum production it is supposed to give me for the area I have. My current system is already converting Ammonia quite well at the moment.

My Gold Fish had a hard time. Most of them died in that week and I realised that one of the big reasons was that the inlets of my suction pipes had too fast flow over it and the fish physically got hurt when they came too close. I manged to find new Koi's which for starters were already 7 cm long and they are now far happier with no losses the past week, eating well and they are nice and active.

The gravel is under investigation. I am busy with the transport engineers in my office to see what the closest source is we can find for either crushed rock or river pebbles that is as far as possible neutral. But again, I will implement that one or two growth beds at a time. I just don't believe in sudden radical changes and reactive behavior.

Of the 16 beds I have 3 that drains very poorly (no plants in there) but the other looks good. It is clear that the consistency of the medium is not perfect but that does not mean it has no place in the system.

Ron is certainly a member with a system running well and I am taking some time to read what he did, but honestly I don't think much of a guy barking one liners of advice. He was also once at a point where he knew bugger all.

As another experienced member I'll back Ron up in his concern over your choice of media.

Coir can work but it requires a completely different flow regime to gravel. As Ron has said contained in pots is an excellent way to use it but not as a substitute for gravel.

Also be aware that your problems may not be obvious for weeks or months. As the fish grow you will get to a point where the beds will begin to fail due to a lack of oxygen.

You could keep the coir and maintain a regular daily schedule of water quality testing which would need to be recorded to reveal any long term trends so that you could see any problems approaching or you could replace with gravel and once cycled only test every week or so.

And Ron is still reading this. My one liners were in response to your reaction to my direction with your photos being too large. ( they still need to be fixed) I was rather upset with your tone. I calmed down and asked others to pitch in to help out because I do still care to see you be successful.
Keep in mind that there are forums where you disobey a moderator, which I am, you would just be banned. That is not the way we run things here, but resizing your photos will make our admin, earthbound, much happier.

Hi Koos, no problem about not wanting to change your media right away. I think you have understood all the dire warnings on your thread.

One of the reasons that you're encountering resistance is that sometimes people arrive on the forums and build something which is not really an aquaponics system and when that fails they tell everyone that aquaponics doesn't work and then they leave. This is obviously not an outcome that people like Ron and Stuart want as they know that a good aquaponics system can deliver food and fish to anyone that can run it.

In that sense they are concerned for your welfare and the success of your system.

Ek weet mos wat a soutie is maar waar ek van daan af kom was enig iemand wat engels gepraat het n soutie. Dit was mos my middle naam.
(EK het lank laas Afrikaans gepraat, ek is jammer as ek die taal gebreek het.)

We got back from Holiday on Monday with my Dad as much a novice as I am, who had to check things out.

The Koi's are doing fine and I lost only a single one this morning but it had fresh blood on the body at the one fin and coming out of the anus. I could see it died only minutes before. I don't know if I accidentally killed it when I moved some of the pipes but that is my guess. Perhaps it could be the other fish as they are very active in the morning, but I did not notice any fighting.

I also see that there are still some of the Goldfish left and they grew well but I suspect there was something wrong with that batch as the fish from day 1 was was not as active as the Koi's. The Kois are now going for week 3 and I lost most of the Goldfish by the end of week 2.

Regarding the media: It took me quite a few weeks to find a source of local gravel that I know should be able to supply more if I need it. There is a guy here who manufactures tumbled granite pebbles and I managed to get a sample yesterday. I am going to order 1 m³ of that, introduce it into a few of the empty growth beds and first let it get some biofilm on before moving some plants over. In that time I can sort out the flow depth too. I will order two sizes - mixed batch from about 5mm to 13mm and larger ones of about 25mm.

The density of the cocopeat (chips and chunks) is not very inconsistent. Most beds flows well but three of them gets like porridge. The ones that I mixed up with chips and loosened, helped quite a bit to get the plants happier and currently only one or two plants close to the water inlet has yellowish leaves. I plant to keep about 1/4th of the beds of the better cocopeat to germinate some difficult seeds and for finer filtration. but if I move over to granite, it will definitely not all in one weekend.

The Baby marrows are quick growers and I should be able to pick off the first ones by the end of next week.

The same goes for the beans, peas and the to a lesser extend the cabbage. They all grow fast.

The herbs like stuff seems to be more tricky and of the ones with small seeds like parsley, most did not even germinate so I need to find a better way there. Planting it 5mm deep as per the packet seems to be one half of the story.

Still lots to learn, still lots of advice to take note of but in the same breath, there is nothing that turns results out better than some experimenting and I will stick to a good component of that.

Thanks for the long update Koos. Much appreciated.

I am sure you know but just in case - don't forget to do a vinegar test on the gravel. You drop some gravel into a cup of vinegar and if it starts to bubble after a few minutes then it contains limestone and must not be used in your AP system as it will cause pH problems forever in a day.

How many Koi are you stocking? Is there any reason you chose Koi? There's nothing wrong with keeping Koi, I am just being curious.

@koosjr,

If you are sure that you want to keep working with cocopeat how about a hybrid approach with Gravel on bottom and peat on top to reduce your issues of drainage and compaction without having to battle the the full pH swings because you would have much less total gravel.

That is why I like the idea of granite. Because it is such a hard wearing rock it should have minimal if any effect on PH. I am busy with an overnight test with some of it standing in RO water see what happens. PH was 6.95 at start. If it does not manage to swing significantly in a small cup with no buffer, then it will be as good as it gets. The vinegar did nothing BTW.


The reason for the Koi is the same as for the Gold Fish. I need a fish that can survive in cold water and I need to go through this winter without any additional heating of my greenhouse or pond to see what the lowest temperature is the pond will go to in mid winter at night. Currently there are about 40 fish of 7-8cm long in the pond.

If the pond goes below 10⁰C then I need to reconsider if Tilapia is worth it. If it looks like I will need extra heating in whatever way then the pretty fish will have to do for now and we can just feed them and enjoy them. But keeping a tank on temperature for the few edible fish one can get out of it if is not a commercial venture and with ESKOM rolling power, that is not the kind of complexities I want to deal with.


It seems that few people grasp that Bloemfontein is not a big place. We have everything here I agree (and for important stuff like hospitals and schools we are spoilt), but our choice of suppliers are very limited. So when I got Gold Fish from guy A and it was a disaster and I suspected a possible bad batch, I had to look at guy B and all he could offer me was Koi. The Koi were bigger for starters which already sounded more promising and he gave it to me at a better price. There are literally only a handful of people around here where I can get fish locally.

For the gravel the same goes. Cobblestones and Granite are both very hard to find in this town. Google it and see. Then you start phoning and half of the few one finds are gone in any case. The try and find that in anything but little 20kg bags... I am not very fond of the crushed rock. Too hard on the hands for starters although very easy to find.

Try and find Greenhouse plastic. A single supplier that can do it. I bought his entire roll and he had to order more. They can't stock large quantities. Up to now, I could find a single person with a regular supply of blue drums.

And that is the reality I need to deal with. Unless I can bring it all over from JHB and cough up for transport, I need to get done with what is close by.

I basically tried it exactly that way by using coco-chip in the bottom and peat at the top but it did not give the result I wanted. The chip IMHO flows like gravel. It does not keep moisture like the peat.

I therefore have my doubts using it on top of gravel.

Mixing gravel and peat maybe. I will try a mixed bed of that and I will use only about 20-30% coco in the mix just for a bit of moisture capacity. I would also like to see if earth worms likes that more than having to cope in plain gravel.

The coir does not really compact if only kept moist. It compacted when it was hydrated and I did not "fluff" it up after that. I do believe through with an established colony of worms it might be great.

As others here mentioned, I also believe that the peat will not be as effective as gravel for bio filtration - after all I have been exposed to sewage plants in my line of work. But that is not to say that it cannot be completely sufficient if one is willing to work on lower densities.

I wanted to give it a try because it is a great thing to physically work with, germinate seeds and the earth worms are certainly very happy in there. In fact, if it is used for worm beds only it might be a perfect work for the media.

You can still use the peat in your seed starters. The vinegar giving no result with the gravel is a very good sign! The granite is tumbled? Does that mean it has a shiny appearance? I bet it will look great.

The granite is tumbled, but not polished, so it does give a shiny appearance as long as it is under water. As soon as it is dry, it just looks like coloured rock so you will not have any splendour on the surface of the growth beds.

That's great, would love to see a photo of the granite as I am not sure what it would look like. I would think that it would be very similar to driveway gravel or is it smoother?



I think that's smart thinking Koos. Testing it beforehand seems like you might get some long term benefits. Once you're more established you might want to consider running a winter species like trout. That might be quite doable in your winter.



I did not realise that you struggle so much with suppliers. I thought that if you're pretty close to Joburg that you probably have similar service. I must say I'm spoilt up here for suppliers but I can't take advantage of it as we're planning on moving sometime soon so I don't want to set something up that I can't take with me. So we each have our own frustrations.

Good Grief, I feel like an idiot as I am having a bloody hard time to get shared images to show in my posts.


This is an early morning one of my fish and I used the phone so it is not very gifted in low light with fast moving objects.




Here then are pictures of the plants.

My Beans. Seems like they are fast growers like the Baby Marrow.




The the Tomatoes. I replanted them from compacted cocopeat to the uncompacted beds in exactly the same order from the bed inlet. This was a great indication for me what wet root does as I am complete idiot with plants. While all the plants now have green leaves, the initial growth was very poor for those close to the water so for me this was profound in terms of my understanding of plants.





The next one are the Broccoli and Cabbages. One can hardly see the difference at this stage.




Then the Baby marrows. The marrows looks great and are very firm. Can't wait for them to be big enough to test.






Cucumbers planted much later than the rest. I walked for weeks to try and find some seed.




Peas. This was the first bed where I noticed that the uncompacted peat works better. However, you can see the plants close to the inlet did not make it. The rest goes well.




This is one of the peat beds which just does not work. It is like porridge even with chip mixed into it. The consistency of the media is very unpredictable.





And for those who want to see what the granite looks like, some of the wet ones and some of the dry ones. BTW, the PH reading this morning in RO water went up to 8.3 and for the overdose of rock vs. unbuffered water I think this is good news. The granite should not make the PH spike and in any case will not wind it up to dangerous levels considering the tendency of systems to lower PH over time.

Last but not least. I finally dropped the last side of the greenhouse so it now will lift flaps naturally when the inside air gets hot. I will monitor it during today to see what the temperature in the tunnel goes to, but my water still moves between 18 and 22 ⁰C in a day.

Now we are already getting night temperatures close to 0⁰C so it might just go through the winter at higher temperatures than what I anticipated.

Readings so far:


PH stays around 7.7. In the early mornings it goes down to about 7.4 and it may go to 8.0 at the end of the day. I am not too concerned and the digital tester works great as one can now take plenty of readings.

On 2014-04-25 the readings were as follows:

NH4 - 0.5
NO2 - 0.4
NO3 - 10

Yesterday and today I did about a 20% water change both days since the I caught the kids on Tuesday feeding the fish without my permission and it was not as clear as to what extend they misbehaved. Sigh.

But a few hours after the change this morning, I measured the following:

NH4 - 0.25
NO2 - 0.4
NO3 - 10


To me it seems like my system have cycled, but I would at best regard it as fragile for the time being. The plants are not well established yet and the way I read it is that it is important to get the plants established to soak up the NO3. Only then one can start doing some more feeding.