Sunday, September 28, 2014

Aquaponics - The reboot

9:19 AM Posted by Grant No comments


I recently decided to start working on my aquaponics system again, this time I took some photos so people can see what it's all about and how it works, for me it provides the best way to kill plants AND fish in the most efficient way possible, whoever let me buy this system has a lot to answer for. Onwards to destruction and possibly eventual cultivation!

What is Aquaponics?

Aquaponics is the combination of Hydroponics and Aquaculture with the former being the practice of growing plants without a traditional soil medium and the later being the breeding of fish under control conditions.

A grow bed contains the growing medium as the substitute for soil (although a medium is not required in some systems) which is connected to a rearing tank where the fish live which is connected back to the growbed. This is what makes this a closed loop system with the nutrients generated by the fish fed to the plants which in turn filters the water.

On top of the obvious benefit of a symbiotic system that produces both fish and plants it also removes the need for chemical nutrients and can be built into many different configurations and scales for different scenarios.

A flood and drain system like the one I use, image stolen from Backyard Aquaponics.

Why Aquaponics?

There are a few reasons and all of them tick boxes that interest me, some more than others however it's a compelling proposition overall.

  • Numerous ecological benefits
This is probably the most important aspect, it localises food production almost eliminating transportation costs, removes the need for harsh chemical nutrients, requires very little amount of energy, the list goes on.

  • Automation
Automation is awesome but being able to tie automation to a biological system with monitoring or by controlling environmental factors is even better. Automatic fish feeders, automated watering and a list of other 0 touch aspects make the process less labour intensive and more productive.

  • Environment control

When you are not bound to locations with good soil quality locations can be chosen on other factors that are favourable to growing, this could mean growing in your backyard or inside under grow lights where even more control is available.

Controlling conditions enables the ability to customise the growing area to suit your plants produces high yields of superior quality and consistency.

  • Potential revenue

Taking the above into consideration if I manage to stop killing everything I may grow plants that are either of no interest to me personally (I use some plants like this as they're harder to kill) or that I have an excess of to sell. Extra money could be used to expand and refine the system, this is of course for epic ewin.

The tank

Since I haven't used the system for a few months I had to check what I needed, buy any parts/plants to get things up and running.

The fish tank after a little cleaning, still dirty but it won't be an issue.
The above is a 920L fish tank, it's fibreglass and I had it shipped from Queensland along with all my original components when I ordered the system, since I wanted to get my current system running perfectly first I didn't need to change anything here.

The top outlet is an overflow with the second a pipe that connects to a mechanical float that detects the water level and connects to a water source to ensure water level is topped up when required. At present it's not much to look at but that will change.

The ground is not exactly level, I had a number of rubber mats I wasn't using so I used these to level out the area and confirmed it was as good as it was going to get with a spirit level.

The tanks final location, this gives it early sun and most of the later day as well.

The grow bed

With the tank positioned the grow bed was mounted, this is one of the reasons it's a good idea to pick a level surface as when filled with a growing medium is is incredibly heavy and having it move would be a bad idea, not to mention that water accumulating in one end and not draining can rot plant roots.

Grow bed sitting on top of the tank.
On the left of the grow bed is the outlet which brings water up from the fish tank via the pump, the brown rocks are clay pebbles which the plants grow in, after taking this picture I added more pebbles I had stored to fill it near to the top.

The white tube(s)

Alright so the white tube sits against the bottom of the grow bed, within it is another pipe with this one slightly shorter and leading directly into the fish tank, another pipe called the bell siphon sits over the top of the inner pipe and contains holes down it's length.

How this works together is some sort of witchcraft however when the water gets above the level of the fixed inner pipe it starts draining into the fish tank, doing this removes the air between the shroud and the fixed pipe which causes suction thus draining the tanks water.

Once the tank is drained air enters the cell siphon ceasing the draining and allowing the grow bed to fill with water again, the process happens on average about every 12 minutes on my system however that may have potentially changed and you'll find out why soon.

Pump / piping

To pump the water into the grow bed a submerged pump is used, it's a pretty standard process, my system has a secondary tap which drains water back into the fish tank, this is useful if the rate at which water is filling the grow bed is too fast.

The reason this is a problem is if the water fills too fast the drain phase never ends as there is insufficient air entering the bell siphon to end the suction and restart the flooding phase. Adjusting this tap decreases the flow while not causing increased pressure by adjusting the main tap to the grow bed with the second tap closed.

Buy all the things!

I already knew I needed to buy some components, some of them due to faults like the above pump being dead and others due to lessons I learned in my previous experience, below is the shopping results.

Enough things to get the system up and running again.
  • Plants
I went with a variety of plants mostly at random although I did buy some lettuce seeds should I kill everything, lettuce grows year around and seeds pretty easily, too easily actually.

Strawberries, Capsicum, Tomato, Chive, Sage and Spinach are the final list, I didn't realise how many plants some punnetts came with so I had to bundle the chives and some of the capsicums with the latter probably a bad idea but I can relocate them if required.

The above plants grow in summer (Not sure about sage) and since there is still more than enough weeks before plants would mature decided I would go with these, can adjust when Spring comes around.
  • Rockwool growing dics
These are the small brown circle shapes next to the pump, not pictured are some very small pots, if required I can use these to germinate seeds assuming I kill everything else which is likely only a matter of time.
  • Canna clay pebbles
This is the sizer of the bag that pebbles come in, if you're ever buying these to fill a grow bed buy more than you need as you're likely under estimating, luckily one bag was enough to fill grow bed completely

One other thing you find out is that these pebbles are very dusty, as soon as they're in the grow bed and the system cycles expect lots of red dust, it's harmless enough however it will get everywhere and I usually water the pebbles to stop this.
  • Pump
Same brand as my old one but more powerful, this caused the grow bed not to drain due to the rate at which it was filling with water. Opening my return tap helped to reduce the flow and ensured it was flooding and draining.
  • Blue ball-things
These are air stones, they are attached to an air pump to keep the water aerated to keep the fishies happy. The stones that came with my old pump were far too light and sat on top of the water, once connected to my pump and tubing they will sit on the bottom of the tank.
  • Black tubing
Part of this tubing is to make sure my air stones can be placed on the bottom of the tank in addition to being able to put the pump on the ground. The other tubing I bought to replace the tubing you saw on my old pump, the reason for this was because it was too short and the pump never fat flush on the ground.

With the pump vibrating all the time it carved a scratch into the tank floor, thankfully the new pump is higher and made up for the difference required in length.
  • Shadecloth
This will cover the exposed area of the fish tank so the fish have full shade throughout summer, should help to keep the water fairly cool.

All planted

With everything connected and pebbles filling the grow bed I planted everything, although before this I had to wash all the dirt from the roots which is a very annoying and time consuming process.

All planted!

The finished system.

The inner tube is the bell siphon anmd the outside is the shroud.

New pump running.


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