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Starting a farm in Jozitown

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  • #16
    Ahhh...the vagaries of borrowed land. I hope you can reach a sensible accord with your new landlord.

    Short answer on the home office system is a qualified yes. The biggest issue with such systems is getting enough light into them. The other prospective problem is the humidity that your system might produce in your home. Both issues can be overcome with a little planning.

    Twenty tonnes of relocatable tomatoes per annum is an entirely different matter. Let me think about it for a day or two. Dutch buckets, perhaps?

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    • #17
      Getting to 20 tonnes per annum will take a while, and by then I should be able to afford something more permanent than borrowed land.

      Perhaps a more immediate goal is to put my 72 sqm greenhouse tunnel to use. Dutch buckets is an option.

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      • #18
        Remind me of the circumstances around the 72 square metres (about 700 square feet) greenhouse. Is this on land that you or Ozzie own/control?

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        • #19
          It is currently on the borrowed land, but it takes two people two days to move it to a new location. I am getting quite good at taking it down and rebuilding it.

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          • #20
            Finding suitable sand is quite a mission. What is passed of as builder's sand in at some quarries is a crying shame. I eventually found a pool filter sand that appears to be suitable. The particle sizes are mostly between 1 mm and 2 mm. It had some fines, luckily not silt, in it, so I had to wash it a few times.

            I have set up something similar to Gary's demo system in my home office:
            • 150 l FT - I will fill this up to about 100 liters
            • 200 l growbed, about 250 mm deep
            • 1200 two tube LED grow light
            • 1200 l/h pump
            I am still debating whether I will add aeration. I'll monitor the DO and another little pump if needed.

            For my fellow Saffas, after I found the filter sand, I learned that there are suppliers that does sand specifically for sports facilities than can supply sand to client specification. I will probably go that route when I scale this up. In the meantime, the little system will keep me entertained.

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            • #21
              Nicol du Toit...iAVs-suitable sand is ideally in the particle size range stipulated...HERE. If your sand contains a predominance of coarse particles, it will drain very well...perhaps too well. Let me say that's a better problem to have than having sand with too much fine material. Anyway, we'll wait and see how your sand works out.

              I assume you tested the sand for carbonates (vinegar test)...right?

              I know next to nothing about indoor systems, so I'll be interested to see how your lights perform.

              Given the small size of your system, I'd regard supplementary aeration as a good insurance...a aquarium air pump would be a good investment.

              Congratulations on getting started. Now, the real learning begins.

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              • #22
                Observations thus far:

                Solids removal is completely different to what I am used to. The fish tank is essentially a settling tank for all but two hours a day. I didn't quite understand why a cone shape bottom is so important until I started, but it is very clear now. When I get to building a bigger iAVS, this is definitely something to keep in mind.

                My sand drains very well. In the areas where the detritus as starting to build up, this does seem to be too much of an issue, but the water does get to the far side of grow beds yet. I did stock at less than half the recommended density due to fingerling availability in the area, so the slow development of detritus is probably to be expected. I expect the detritus build up to speed up when the fish get to around 20g each.

                My tilapia rendalli live on a steady date of lettuce, and I supplement with commercial feed once a day. I scattered some lettuce, egg plant and tomato seeds to track the movement of water through the growbeds. The seeds have germinated on the far end of the growbeds so there is moisture, albeit below the surface. I planted some celery seedlings in the growbed which are growing happily.

                My pH is running around 6.4, water temperature between 22C and 24C. I purposefully kept the water temp a bit lower while the system starts up. I've known warmer water and NO2 spikes to make fish very unhappy.

                Apart from observing the leaf colour, I don't really know what is happening nutrientwise. Would it make sense to measure EC levels?

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                • #23
                  I am getting a bit impatient with the slow progression of my iAVS which, ironically yet unsurprisingly, is caused by my impatience to get started in the first place.

                  I tracked down another quarry, and they sent me their screening results. To my untrained eye, the 1.1mm batch is a better fit. What would the expert opinion be?
                  Attached Files

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                  • #24
                    No expert opinions around here at the moment...we're all on a steep learning curve.

                    Of the two samples, the 1mm one would be my choice, too. Even then, it's at the top end of the particle size range. That's much less of a problem than having too much fine material in the mix...assuming that it proves to be any sort of obstacle at all.

                    How's your small iAVs going...anything to report?

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                    • #25
                      Quoting my previous post,
                      Observations thus far:

                      Solids removal is completely different to what I am used to. The fish tank is essentially a settling tank for all but two hours a day. I didn't quite understand why a cone shape bottom is so important until I started, but it is very clear now. When I get to building a bigger iAVS, this is definitely something to keep in mind.

                      My sand drains very well. In the areas where the detritus is starting to build up, this doesn't seem to be too much of an issue, but the water doesn't get to the far side of grow beds yet. I did stock at less than half the recommended density due to fingerling availability in the area, so the slow development of detritus is probably to be expected. I expect the detritus build up to speed up when the fish get to around 20g each.

                      My tilapia rendalli live on a steady date of lettuce, and I supplement with commercial feed once a day. I scattered some lettuce, egg plant and tomato seeds in the grow beds to track the movement of water through the growbeds. The seeds have germinated on the far end of the growbeds so there is moisture, albeit below the surface. I planted some celery seedlings in the growbed which are growing happily.

                      My pH is running around 6.4, water temperature between 22C and 24C. I purposefully kept the water temp a bit lower while the system starts up. I've known warmer water and NO2 spikes to make fish very unhappy.

                      Apart from observing the leaf colour, I don't really know what is happening nutrientwise. Would it make sense to measure EC levels?

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                      • #26
                        Apologies, Nicol...I neglected to check the date of your last update. Thank you for doing so.

                        By way of response:
                        • The solids do settle in between irrigation events. We advise feeding so that the fish purge themselves of solid waste prior to an irrigation event in the morning...and at around 2.00pm in the afternoon...prior to the overnight shutdown at around 8.00pm. That minimises the waste that is left standing in the tank overnight.
                        • Cone-shaped fish tanks...or those with a curved/sloping bottom are definitely preferred over those with a flat bottom. While solids can be focused in the centre of a flat-bottom tank...by the creation of a circular movement of the water in the tank...it's much easier if the tank is the right shape at the outset.
                        • Plant growth in an iAVs is the product of having a given number of fish...eating a stipulated percentage of their body weight/day...to feed a particular number of plants. It's predicated on feeding a commercial diet. Mark spoke of having 80 fish (15g each) being able to support two tomato plants over 100 days. I'd recommend that you feed the commercial ration to the point of satiation twice a day...particularly while your system is still settling down.
                        • EC means little in an iAVs. The best guide to what's happening with your plants...outside of laboratory tissue analysis...is the rate of growth.
                        • Everything seems to be going well enough, at this stage. This is a little test unit...and a good opportunity for you to firmly inculcate the iAVs method. I'd urge you to focus on things like feeding so that you experience the plant growth (and other attributes) that your system should be capable of.

                          Is the bottom of your tank clean...and the water clear...or are solid remaining in the tank after irrigation events? I can show you how to address this if it's a problem for you.

                          Any photos?

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                        • #27
                          This is great learning experience..

                          I am feeding the fish in the mornings, before the first irrigation cycle, but not always in the afternoon. I've been thinking about getting one of this fish feeders for when I am not around. My tank is surprisingly clean. I am also very impressed with the clarity of the water. At the moment, I'm more interested in understanding how the system behaves and producing healthy plants than trying achieve record harvests. As my confidence builds, so will my willingness to push the system.

                          I'll try and remember to take some pictures.



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