Backyard Aquaponics
A place to discuss aquaponics

OK, I planted my first seeds on 2014-03-16 and the tomatoes was the first to push out some leaves 4 days later.

My system started with the PH rather high at about 7.8 and I left it at first to see what happens. There was no change so I decided to adjust it down yesterday to about 6.2.

Currently my water temperature raise to 22⁰C in the day and drop to 18⁰C at night.

It seems like the nitrogen cycle is going now and I am already reading about 5ppm on the Nitrates.

Of all the plants the Spanish is most unhappy at the moment and in all the beds there are plants where the leaves are a yellowish and some plants that are good.

Interesting though is in my growth beds I decided to initially let the water in on one corner and out a the back. I therefore have a gradient from wet to dry.

The tomato plants close to the wet part struggles and the one at the furthest corner is the best.

With the peas, there is no difference, all the plants are strong.

With the Coriander it is the other way around. The plants in the wet corners seems to do best.

Baby marrows grows very strong, but some plants also have some yellow leaves.

Now I will see if the lower PH helps with the yellow leaves.


I also got myself some earthworms earlier this week and introduced them into the growth beds. I am quite interested to see what will happen to the cocopeat.


I introduced 50 small goldfish yesterday for the following reasons:

1. I first want to go through this winter and see what my tank temperature will drop to without any additional heating and the see what needs to be done to raise Tilapia. The Goldfish will easily tolerate the lowest temperature that I expect the tank will be.

2. PH. Same story. I would like to see at what PH my system settles on it's own without me trying to manage or control it. Goldfish can function in a wide PH range.

I was forced to buy petshop fish this time so it was rather expensive, but having fish transported form another town would be much more for transport alone. That is about the only drawback of living in a small place. We always pay for transport.


There are already many little larvae in the water and some of the the Goldfish was pretty much in feeding frenzy when they got in the water with a specific one that fed for more than an hour. I will wait and see because I know these little guys can eat them selves to death so I might loose a few but right now all of them are still fine. Seems like petshops don't worry to give them food.

I will also hook up my old little Campbell Scientific CR200 data logger soon to measure greenhouse temperature, ambient temperature, water temperature and growth bed temperature. Simple and sometimes a bit bitchy to program, but very robust.


In summary then:

1. My approach will be more of a wait and see and measuring some values for now.

2. My aim is to get a system that can function with minimal human adjustments.

3. I want to go with the flow in terms of local weather. This means that production in winter months will decline.

BTW, my pics are now linked from Dropbox so resizing is not a problem.

This morning, PH went back to 7.2, so I am going to just leave it for now.

7.2 is a great ph. Why would you want to change it?

Most sources reckons that for a variety of plants it should be a bit lower. I thought there was some merit in that. But as said, I don't want to mess with it too much.

Fish are all still fine in spite of the heavy feeding yesterday.

A higher ph helps with cycling.

The last week and a half was quite a steep learning curve.

I figured out why some of my plants had yellow leaves and that was because the cocopeat was way to much compacted. This is as a result of how I hydrated the blocks.

What I did was to pour in many litres of water in a growth bed to saturate the dehydrated blocks and left it to drain naturally. That caused the fine cocopeat to compact.

The thing that made me raslise was was wrong, was by coincidence. Some of the blocks of coc chip was not good quality chip and there was almost 80& fine material in there. I had to make a plan to be to use some of that and realised taht the plants in those beds grow very well.

I then immediately took a few of the other beds and mixed the chip and peat up well, but the mix expanded so much that I had to remove about 25 litres of media and put in into one of the empty beds.

I planted some seeds there again and the looser peat seems to do the trick. It drains very well and I can push in my had deep before hitting water.


About the fish:

It was a black week for the fish and I lost probably about 50% of them in this week.

About 6 of them ended up in the pipeline feeding the growth beds but at least my lines are done such that it is quite easy to clean.

Many of the fish flaked and died and that was when one of my friend who is quite an expert in breeding with goldfish told me I need to put in salt immediately. So I searched this forum and saw he was indeed right, but that I can just not put it in at the level that they do for aquarium fish only. they work on solutions of at least 5 ppt.

I then mixed in my system at 2 ppt and it seems to work well as the flaking stopped after two days.



I also changed the circulation of my tank. As it is a circulate tank, is is normal for any sediment to settle right in the middle. I actually did not realise how much it was until I took a broom and scratched around there.

The then modified the inlet pipe with a funnel at the bottom and large holes that sits right in the middle of the tank. This seems to work excellent and although my water was of good clarity in any case it is now even better. The radial flow should be able to feed almost all sediment to the growth beds.

I also made a bypass for now to increase the tank circulation but still have a bit less water going to the growth beds. With that I made a small mod to the supply pipe to such in air with a venturi effect to help add oxygen. the same venturi doubles as an air inlet to prevent water from gravity feed back into the sump.

I bought myself a good quality digital PH tester with accuracy of 0.01 as the test strips are quite expensive if one needs to take readings often.

Oh, and the greehouse works excellent to keep temperatures high. I closed off the entire back side and 3/5ths of the front side. Day temperatures rise into the early 30's and the tank now picked up to 26⁰C at the end of the day and dropped to 22⁰C this morning with ambient temperature at 11⁰C.

Initially I wanted to make automatic roll up sides but I prefer to first try and get things to run on self governing natural principles because when one gets it right, there is nothing better.

I am therefore positive that it might be possible to stay above 10⁰C without extra heating as I still have some sides to close in colder weather.

This has been quite a lot of fun up to now and I enjoy it immensely. It is great to have a hobby where I can spend many free hours outside instead of browsing the internet.

The children too are spending hours watching the fish and they gave them names. That helps me as they keep better count how much is still in the tank.

Rethink your media.

Not now.


If it does not work, then at least I need to observe first and understand why.

Observation 1: it compacts too easily
Observation 2: your ph is out of whack
Observation 3: the tannins make it hard to see the fish
Result, you lost 50% of your fish

DUDE! I am trying to help you. The whole point of posting on a forum is so people can steer you away from mistakes. Using an unsuitable media is a mistake. Cocopeat is an unsuitable media. It would be fine if you had the coco peat in planters on top of capillary matting as a component of your system. But it does not work as a biofilter, which is the whole point of gravel.

On point 2 you contradicts yourself. You said 7.2 is great and my PH is 7.2 so you asked why I tried to change the PH. It went back to 7.2 the next day.

Just keep in mind that on forums info is not very organised. It is very difficult to filter out the good info from the bad.

I appreciate your input, but do know that I test what ever you say with some more reading.

Upon rereading, you are right about the ph. It has been fairly consistent at 7.2. Now, there some EXPERIENCED members that have done some flow through wicking beds. Again as part of their system that has adequate bio filtration. Please read up, the search function is under used.
That being said, I see an AP burnout in your future, and I am trying to prevent that. If there is a river near by, you could get your gravel for free.

Hi Koos,

Martin here from Joburg. I think your system set up is great and your handiwork is impressive.

I do want to raise an issue - I am also concerned about your choice of grow media. The most important aspect of grow media is that it should be a neutral/non-reactive substrate and a good home to bacteria. It should also provide good physical support for your plants.

Going through wikipedia there are a number of notes that raise red flags for me:
"Coco peat from Sri Lanka and India contains several macro- and micro-plant nutrients, including substantial quantities of potassium. This extra potassium can interfere with magnesium availability. Adding extra Magnesium through the addition of Epsom salts can correct this issue."
This means that you're not fully in control of your potassium and magnesium additives your system, there could be a bad imbalance you won't be aware of. Your grow media is not neutral. It also contains "contains several macro- and micro-plant nutrients" what are these? How will they affect the plants you're growing?

"Some Coco peat is not fully decomposed when it arrives and will use up available nitrogen as it does so (known as drawdown), competing with the plant if there is not enough."
This is not good.

"Poorly sourced coco peat can have excess salts in it and needs washing (check electrical conductivity of run-off water, flush if high). It has a similar cation exchange capacity to sphagnum peat..."
Probably not a big problem but it could affect the salinity of your system without you being aware of it.

"Coco peat generally has an acidity in the range of pH - 5.5 to 6.5. It is a little on the acidic side for some plants, but many popular plants can tolerate this pH range."
This is too low for an AP system to flourish unless it stays in the really high part of this range - around 6.5. So you will be fighting the pH just as much as you said you would the gravel. The benefit with gravel is that you can check the reactiveness with the vinegar test. If it is neutral you can feel confident it is safe to use and it will stay neutral.

"Coco peat can be re-used up to three times with little loss of yield."
This to me means that you have to replace it after three "uses" or seasons. Gravel lasts for decades although it might need to be cleaned out every 5 years or more depending on how well your grow beds function.

"Coco peat from diseased plants should not be re-used."
This means that if you have a disease outbreak in your grow beds you have to replace your grow media. This is not the case with gravel.

Under biosecurity risks:
"Coco peat can harbour organisms that pose a threat to the biosecurity of countries into which it is imported. Coco peat has been imported into New Zealand since about 1989 with a marked increase since 2004. By 2009 a total of 25 new weed species have been found in imported coco peat. The regulations relating to importing coco peat into New Zealand have been amended to improve the biosecurity measures."
Also not good.

All of these remarks make me feel that coco-peat is a very poor grow media.

In one of your comments earlier you mentioned something like: "there have been many members using coco-peat successfully". I don't think this is accurate. I have not seen a single member use coco-peat successfully and I have seen one failure.

I really believe if you change your grow media you will increase your likelihood of success. If your friends and neighbours are interested in this process it would be great to show them a flourishing system. That keeps delivering good produce for years to come. While your system may be successful initially it could crash later unexpectedly due to one or more of the reasons stated above.

Ongelukkig is daai soutie Ron reg!

Regards, Martin.