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Starting a new Aquaponics System

BY Leslie Ter Morshuizen

We recently erected a demonstration unit of our Circle of PlentyTM, (CoPTM) a banded, medium-sized aquaponics system designed to fill the niche between the hobby systems (such as `Lappies’) and commercial systems.  The logic being that schools, prisons, villages, retirement complexes and other communities will benefit from having access to a proven system on which they can learn the skills of growing their own fish and vegetables, while also benefiting from the high nutritional value of these aquaponically grown crops.
 
Starting a new system is always a good time to test theories and to set good habits in place.  Since we erected our 1st commercial aquaponics tunnel in 2012 I have been advising people to follow a specific path when maturing a new system, and the erection of the Circle of PlentyTM provided the perfect opportunity for me to implement and quantify this approach.
 
I advocate the following sequence of actions as being optimal to get your system to maturity as quickly as possible:
1.      erect and fill the system, then switch on the pumps to tweak the flows per bed, ensure the beds flood & drain correctly, and that the sump handles the variable flows
2.      if temperature control is required switch this on now to obtain the correct water temperature for your crops
3.      next, stock the fish into the tanks and plant the beds with seeds or seedlings
4.      perform the following daily tasks – feed the fish, measure the pH, EC, water temperature, ammonia, nitrite and nitrate
 
The analysis and management of these readings is important and should proceed as follows:
·        chart the results as this displays patterns that are easily assessed
·        if the ammonia or nitrite concentration reaches 0.5mg/? then add BioPond (1 cap per 5m3) daily
·        if the pH drops to below 6.5 then add adequate potassium carbonate, calcium carbonate or a similar, appropriate buffer to keep the pH close to 6.5
·        if the EC is too low according to the requirements of your crops then add 1? SeaGrow to the sump weekly
 
The expectation is that the pH will initially remain >7.0 depending on the source water’s chemical characteristics.  This is fine, just wait and as the system matures the pH will drop at some point and it is then that buffering is required.  I do not advocate adding substances to lower the pH.  The chart below displays the pH measured in the Circle of PlentyTM during the 1st 6 weeks of operation, showing clearly the fall of the pH and the impact of addition buffer.  Please note that our source water is extremely pure, so the pH drop happened almost immediately.  In a system using harder source water this effect would be delayed.

 

Ammonia and nitrite will increase and need to be managed to prevent them attaining toxic levels for the fish, and the addition of BioPond will achieve this.  The chart below shows that there is 0.2mg/? nitrite in my source water (a trout RAS) but no ammonia.  As the fish feed and produce waste within the CoPTM the levels of both ammonia and nitrite rise.  The data is not smoothed for effect, this is real data and the fluctuations are not atypical of what we find in a new system.  The impact of adding BioPond to shorten the bacterial maturation cycle and to prevent the ammonia and nitrite concentrations become toxic can clearly be seen.  Without BioPond, both levels can become toxic and the bacterial colony typically takes around 3-4 months to mature, here it took 6 weeks.
 
The data presented above demonstrate the results obtained when starting up a new aquaponics system, and monitoring and managing the water quality.  It shows clearly that fishless cycling is unnecessary, enabling us to get to full production ASAP.  We ate the 1st crops out of this system last night, 6 weeks after completion of construction!  Not too shabby for mid-winter.
 
For those interested in the Circle of PlentyTM please email me for additional information.  The test kits, buffer and BioPond are all available on our online store.

 June 09, 2018
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