Preface

Reconnecting with where we left off in the Introductory iAVs Course is a useful place to start this course.

The Intro Course summary captured the essence of that course in what we referred to as the iAVs Recipe.

We said it was like baking a cake…and all one had to do was follow the recipe – to produce satisfying results. The iAVs Recipe is a ‘quick start-up guide’ – a means of being able to produce a satisfactory result with a minimum of fuss – straight out of the box.

The iAVs Recipe

Essential Equipment:

  • Fish tank
  • Sand Bio-filters, aka ‘Grow-beds’ (start with one filter per fish tank)
  • Water pump – capable of emptying the tank in an hour – at the rated head.
  • Air pump and air stones (ceramic stones best)
  • Timer – digital recycling

Essential Ingredients:

  • Sand – as per specification.
  • Furrows – as prescribed.
  • Water  – potable – and clean air
  • Feed  – use a formulated ration
  • Light  – natural sunlight is best
  • Fish – species selection is a factor
  • Plants –  fruit bearing and/or of mixed ‘type’ (Families)

Instructions – highly recommended

  • 1:2 fish tank volume to sand bio-filter ratio (for the number of fish indicated below, and with large fruiting plants)
  • Water – adjust pH to 6.4 (plus or minus 0.4) – rainwater is usually best.
  • Provide at least 12 hours of light per day – more is better – plant species-dependent.
  • Start off with 80 to 100 x 15g fish per 1000 litres.  (grown to 250 to 300 g, then start to cull larger fish)
  • Ambient air temperature – plant species/season-dependent in the 15oC – 35oC range.
  • Grow a mixture of leafy greens, and legumes but have at least 50% of the growing area in fruit-bearing crops.
  • Feed at least twice per day – last feed not later than 2:00pm.  (earlier in the tropics or hemispheric winter)
  • Irrigation volume and frequency – designed to 2 tank exchanges per day – two hours of pumping – work on 8 cycles per day to establish the duration of each flood cycle.
  • Irrigation volumes and frequency  –
    • pump 25 to 30% of tank volume (15-20 min ON) once every 2 hours starting at dawn, and finishing at dusk.
    • complete one full tank exchange (3-4 ON cycles) after the early morning fish feeding
    • complete another full tank exchange after the mid-day fish feeding and before dark.
  • Water Temperature –– 25oC – 30oC.

Now, if you do nothing more than follow the recipe – you can anticipate similar results to those demonstrated by Mark McMurtry in his research trials – and subsequently by Boone Mora in his successful USDA-sponsored commercial trial.  

Further to that, we said…

“Indeed, since Mark never set out to optimise anything (that wasn’t the purpose of the trials), it’s quite possible that you will exceed his outcomes.“

And that’s where this course – ‘How to Optimise an iAVs Sandgarden’ – enters the picture.

Before we embark on the optimisation of our iAVs sandgardens, however, we need to expand our understanding of some of the method’s aspects.

To that end, we’ll take a closer look at the following:

  • Sand
  • Water
  • Fish
  • Plants

The Mirriam-Webster Dictionary defines ‘optimise’ as – “to make as perfect, effective, or functional as possible” – so we’ll be going with that.

We should be clear from the outset that optimisation – in an iAVs context – is not about improving the iAVs system. The method requires no structural improvement – it’s perfect the way it is.

But that’s not to suggest that we can’t fine-tune an iAVs – and the systemic opportunities include:

  • Component Ratio – fish tank to sand biofilter V:V
  • Irrigation volumes and frequency
  • Sand Particle Size Range

Making considered changes to these aspects enables us to adapt our iAVs to our specific situation. You can vary the component ratio. You can adjust the irrigation volumes and frequency to ensure the right balance between retained moisture and drainage. And you can slow things down if your drainage rate is too fast.

The biggest opportunities for optimisation, however, lie in managing the environment in which our fish and plants are being grown.

So, we’ll be learning about;

  • Light
  • Temperature
  • Humidity

…and what their management/control entails.

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