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Organic Hydroponics

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  • Organic Hydroponics

    When I hear the term 'hydroponics' a variety of growing soilless growing strategies come to mind including:...using a range watering regimes and substrate types including:The other defining feature is that the plants grown in hydroponics are usually fed with a mix of inorganic chemical compounds that are formulated to meet the nutritional needs of specific plants.

    Recently, my interest has been piqued by something called organic hydroponics.

  • #2
    In hydroponics a nutrient solution is mixed and circulated in order to feed the plants. A hydroponically grown plant receives all of its nutrients through this solution and not the medium it’s grown in. This nutrient solution is comprised of a combination of inorganic compounds such as calcium nitrate, potassium nitrate, monopotassium phosphate, iron chelate and many others that, when dissolved into water, dissociate into ions ready for immediate uptake by plants.

    In organic hydroponics, the nutrient solution is comprised of all-natural and organic fertilizers and micronutrients. This can be achieved through a variety of ways, including the use of a compost tea, which provides many of the micronutrients a plant requires.

    Anyway, on the heels of a mediocre season with my soil-based plant growing systems, I decided to learn more about organic hydroponics. I could have used any one of several hydroponics methods but, rather than buying more stuff, I decided to cobble something together from my existing collection of growbeds, tanks, pumps and other aquaponics flotsam.

    To that end, I filled a couple of shallow grow beds with gravel (for which I usually have a healthy contempt) and rigged up a nutrient tank, some pipework and a small submersible pump.

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    I propose to grow some silver beet in here initially.

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    I have yet to put any nutrients into the system. The discolouration of the water is the result of clay and/or powdered sand that has washed off of the gravel.

    Assembling this simple system is the easy part. Producing an effective nutrient solution is the next...and rather more complex...part of the project.


    • #3
      So,........ you're putting the iAVs build on the back burner?


      • #4
        To be candid, I'm somewhat confused about what I'm doing. After nearly 14 years of integrated aquaculture in its various forms, I'm feeling burned out...and questioning the relevance of what I do - to the point where I don't feel like doing much of anything.

        I have too many interests...and I'm I need to work out what is really important to me and focus on that.

        This unit is something that came a response to a perceived need to do snap myself out of the malaise. It was also a knee jerk reaction to a very ordinary soil-based gardening season.

        How this system ends up...and whether I build anything else...depends on the outcome of my deliberations in the coming weeks.


        • #5
          Almost three weeks after my last post, the motivational lapse has subsided and the pathway is clear.

          Yesterday, I planted this system out with a mix of kangkong, French beans, bok choil and spinach.

          While this system is destined to be organic hydroponics, I still have to build a nutrient brewer/biofilter - and I'm curious about the difference between organic hydro and true hydroponics. So, I've decided to run it initially as a straight hyrdo system...using nutrients out of a bottle.

          Today, I drained the gravel system and refilled it with clean rainwater. I mixed up 150mls each of Canna Aqua Part A and B and stirred them into the nutrient reservoir...where they are to stand for a few hours.

          Later today, I'll start the pump and begin circulating the nutrients through the bed...and things should start growing shortly after that.


          • #6
            I kept these seedlings for too long before I planted them out in the gravel they were a bit leggy and jaundiced.

            They've had a few days to get established so I'll take the shade cover off to enable them to get more light.

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            • #7
              The performance of the gravel hydro bed (currently running on bottled nutrients) has been unspectacular. While the kangkong and the pak choi went quite well, the beans and silver beet (Swiss chard) were ordinary to say the least. My most recent experience of kangkong reminded me of how fast it grows...and that chickens love it. It has a very neutral taste and I'm looking forward to trying it in a stir-fry dish.

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              I've built a small organic hydro biofilter/brewer. This will enable me to produce my own nutrient solution.
              Attached Files


              • #8
                My current hydroponics installation consists of the two (8' x 3') gravel beds...and a 72-hole Boxsell NFT system. Both systems are coupled together and drain into a single nutrient reservoir. I'm now using a 2-part powder nutrient mix which represents much better value than the bottled stuff that I used for the startup. I've grown pak choi and kangkong...and I've been harvesting useful quantities of both vegetables...largely for use as green feed for our chickens.

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                I've been really impressed with the rate of growth of the kangkong. It's quickly taking over the gravel grow beds, at which point, it will provide a daily harvest...for us or the chickens.

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                As our capacity to produce vegetables grows, so has our need for healthy seedlings. Buying seedlings...particularly at the level that we're now using far too expensive, so I've been experimenting with various ways of growing from seeds. This little ebb and flow unit is filled with Canna clay pebbles. I simply sprinkle the seeds over the clay pebbles and, within a few days, I have hundreds of tiny pak choi, silverbeet or kale plants. Transplanting the seedlings is quick and easy.

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                It's been a long time since I grew plants using pure hydroponics...and I have to say that I'm enjoying the consistency and productivity of the method. So long as I put seedlings and nutrients into the system...and keep the pump running...the clean fresh food just keeps coming.


                • #9
                  A few weeks ago, I built a little biofilter/brewer to enable me to learn more about cost-effectively turning organic substances into plant-available nutrients.

                  The biofilter consists of a 20-litre plastic drum into which I’ve placed a 750-litre/hr pond pump.

                  The 20-litre bucket is fitted with a lid into which I’ve drilled some small holes. A 10-litre bucket sits on top of the 20-litre drum – supported by the lid with the holes. I’ve placed a coir garden pot liner inside of the 10-litre…and part-filled it with coarse sand.

                  The sand will filter out any solid materials and will serve as bio-media…housing the nitrifying bacteria and other microbes that will convert the organic substances that I want to decompose so that they become plant-available.

                  This simple plumbing arrangement allows me to adjust the rate of flow through the top bucket while also stirring – and aerating – the contents of the 20-litre bucket.

                  Anyway, I’ve just started it up and my first trial will involve one of the most accessible organic substances of all – human urine.

                  Notwithstanding, it’s alleged ‘yuk’ factor, urine is very interesting stuff. It contains valuable nutrients which are wasted by flushing it down the toilet. But its role in the waste cycle doesn’t end there. We waste millions of megalitres of potable water – using billions of dollars of infrastructure – flushing it into waterways where it (along with the other substances in wastewater) harms the aquatic and marine environments.

                  For those who like a few details...

                  Tuesday 11th June 2019 - filled Biofilter/Brewer (BFB) with 15 litres of rainwater - pH 6.5 - recirculated through sand biomedia for 24 hours - urine capture started 0600 hours.

                  Wednesday 12th June 2019 - 1730 - pH of BFB water = 6.5...prior to addition of urine. (Urine pH = 5.7 - added 250ml) Water Temperature 19o C - ammonia = 8.0+ (off the scale - very dark green). Nitrite = 0

                  Thursday 13th June 2019 - pH 7.0 - water temperature 19oC - ammonia even further off the scale (almost black) - Nitrite = 0 (not surprisingly) - drained half the water from the BFB and replaced with fresh rainwater - ammonia still off the scale - drained half of the water again - ammonia = 5. If I'd waited for the ammonia levels to drop - of their own accord - it would have added several days to the cycling process.

                  Two observations from the BFB startup, so far. First, urine takes very little time before it starts to produce ammonia. Second, a little bit of urine goes a long way.

                  Friday 14th June 2019 - pH 7.2 - water temperature - 21oC - ammonia = 8.0+ (off the scale). Drained half of the water and replaced with fresh rainwater.

                  Another observation: Urine is the gift that keeps on giving. It obviously continues to yield ammonia over an extended period of time.

                  Saturday 15th June 2019 - at 0800hrs, I did another ammonia test...and the reading was still, this time, I drained the whole 15 litres in the bucket...leaving only the water that was trapped in the sand. I put another 15 litres of water back into the reservoir.

                  This morning, I took out all of the water - except that trapped in the sand - and put 15 litres of rainwater back in.

                  That seems to have fixed the problem since the reading is now at 4.0...ready for the next stage of nitrification. The only inhibitor to cycling now is the water temperature... currently at 14 degrees I've put an aquarium heater - set at 30 degrees C - into the reservoir. That'll kick the transition from ammonia to nitrite along a bit.

                  Sunday 16th June 2019 - at 0900hrs...pH was 7.1...ammonia = 4.0ppm...temperature = 30oC. The system is now poised for nitrification to occur. Aside from continuing to recirculate the water, nothing else is required. In the coming days, the ammonia level should drop to zero...and nitrite levels will begin to rise.

                  Monday 17th June 2019 - at 0930hrs - pH was 6.9...ammonia = 4.0ppm...temperature - 30oC.

                  Tuesday 18th June 2019 - at 1700hrs - pH was 6.8...ammonia = 4.0ppm...temperature - 30oC. This trial has now been going for one week. It should be noted that I only got the ammonia level within nitrification range about three days ago. Prior to that, it was too high for nitrification to proceed. Now, it's just a waiting game...waiting for the ammonia levels to drop to zero...and for nitrite production to begin.



                  • #10
                    ...and for those people who still like numbers...

                    Wednesday 19th June 2019 - 1730hrs - pH was 6.3 - Ammonia = 0.0 (zero) - Nitrite = 0.0 - Temperature = 30oC. Note: The sudden drop in ammonia - from 4.0ppm to zero - a scheduled soft landing. Within the coming days, Nitrite levels will begin to rise.

                    Thursday 20th June 2019 - 0700hrs - pH is 6.1 - Ammonia = zero - Nitrite = Zero - Temperature = 25oC - (finger drumming sound)

                    Friday 21st June 2019 - 1515hrs - pH is 6.4 - Ammonia = = zero - Nitrite = Zero - Temperature = 31oC - (finger drumming sound)

                    Saturday 22nd June 2019 - 1900hrs - pH is 6.6 - = zero - Nitrite = Zero - Temperature = 28oC - (finger drumming sound)

                    Sunday 23rd June 2019 -


                    • #11
                      Hi Gary,

                      How have you been going with this experiment?