While The Queenslander relies on traditional filtration devices for water quality management, it is the arrangement (and the management) of those components that provides the system with its productive edge.
Click on diagram for larger view.
The nutrient-rich water leaves the fish tank through a tank overflow (which draws from the bottom of the tank) and flows into a sedimentation and clarifier tank.
The sedimentation and clarifier tank is fitted with filter mats which trap all sedimentary solids and much of the suspended solids, too.
The water then flows into a duckweed tank where its velocity decreases sharply – and any smaller sedimentary solids are allowed to settle out.
The duckweed also provides for some bio-remediation in that the plants have a fondness for ammonia (particularly in its more toxic un-ionised form).
The sediment that accumulates on the floor of the duckweed tank is vacuumed out weekly (at the same time that the duckweed is harvested).
The water then enters a grow bed filled with expanded clay pebbles which traps any remaining suspended solids. (The management of this grow bed is central to the enhanced operation of The Queenslander and is discussed more fully in my next post).
The water drains from the grow bed into a sump tank. A trickling bio-filter is mounted above the sump tank. A pump is located in the sump tank.
While some of the flow from the pump returns to the fish tank, the rest of it is diverted to the trickling bio-filter which drains back into the sump tank.
The constant recirculation of the water in the sump tank through the bio-filter ensures that the water is both clean and very well aerated.
Another important benefit of the trickling bio-filter is that, in the event of a disease or infestation in either the fish or the plants, I can disconnect the fish tank from the growing systems. This means that each organism can be treated without detriment to the other.
Mounting the bio-filter over the sump tank (rather than over the fish tank) has reduced pumping head by up to a metre which means that we can now move more water for the same cost…….or the same amount of water at lower cost.
The liquid waste that results from cleaning the clarifier pads, duckweed tank and the grow beds contains valuable nutrients which will be recovered and returned to the system. It is pumped to an aerobic digester where brisk aeration of the water mineralises the solids.
Once the air supply to the aerobic digester is turned off, the sludge settles out very quickly. The nutrient-rich liquor can then be decanted and returned to the system. The spent sludge is good for the worms or compost heap.
In my next post, I describe how grow bed management is used to support component location in the cost effective removal of solid wastes.
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{ 10 comments… read them below or add one }
Hi Gary
You have obviously put a lot of thought and research into the Queenslander. I have 4 questions if you don’t mind:
1. Is it continuous flow rather than ebb and flow?.
2. Is your clarifier something that we could purchase?
3.Do you think you could describe your biofilter a bit more – I can’t quite picture it.
4.”The nutrient-rich water leaves the fish tank through a tank overflow (which draws from the bottom of the tank) and flows into a sedimentation and clarifier tank.” – I can’t quite picture how the overflow draws from the bottom of the tank.
Thanks
Trish
Trish…..the grow bed is continuous flow – but the bio-filter may yet end up operating as flood and drain.
2. We’re looking at a couple of clarifier options – stay tuned!
3. The bio-filter in its simplest form is a container filled with suitable media. The water enters the bio-filter at the top and percolates down through the media before draining out of the bottom of the filter.
4. The tank is fitted with an outlet at the optimum water level. A tee is fitted to the outlet and a piece of pipe attached to the bottom leg of the tee…..so that any water that leaves the tank can only do so via the pipe. As new water enters the tank, it displaces water through the pipe.
Can we get some real photos in detail of the setup? i would love to see them!
jon…….we’re still assembling the components. I hope that we’ll have something for you soon.
Hi gary…just like to say WOW and THANKS for all the valuable and insightful info you post here.
With regards to solids removal in your system – by having a stand pipe in your fish tank that only allows water to enter at the surface of the water level (rather than an open drain at the lowest point in the tank, without a standpipe) how do you get all the solids out of the fish tank – don’t some solids fall to the bottom of the fish tank and collect there?
Jodi….the standpipe in the fish tank is open at both ends. The water enters from the bottom and rises up the pipe and exits the tank and flows into the clarifier. The standpipe is open at the top to prevent the creation of a syphon effect which would drain the tank.
The standpipe is designed this way so that the solids (most of which do settle) are drawn up the pipe. Those solids that do not enter the pipe can be removed with a simple displacement vacuum arrangement.
Thanks for this info Gary ….. I have a trickle biofilter made from a 4 drawer plastic storage bin from Walmart (cost $3.00 at a thrift shop) that sits on the fish tank and works really well, except for one thing ….. by pumping the effluent into it, it went anaerobic in a couple of months, and poisoned the tank so I lost several fish – it smelled like sewage! Now I am planning to put in a swirl filter as a clarifier with a tap in the bottom to take out the solids and get a longer time on the biofilter. Thanks to your drawings of the “Queenslander” I have a better picture of how I need to set this all up. It’s still winter here, so I won’t have the duckweed tank or the growbeds, but I think I can make it work better by modifying my setup to look more like yours. Once again, Thanks!
Jackalope…..an effective trickling bio-filter can be made from plastic drum filled with oyster shells. Obviously, the drum needs to be robust enough to support the weight of the shells.
The water is pumped in through the top of the drum and percolates down through the media before draining out through the bottom of the drum.
They work best if you screen sedimentary solids prior to the water entering the bio-filter.
To ensure even distribution of the water through the media, we use a plastic dishwashing bowl (will lots of holes drilled in the bottom) that sits snugly in the top of the drum. This acts like a shower head.
These simple trickle filters are cheap to make and provide for good nitrification and aeration. They are easy to make and maintain.
My first attempt at aquaponics is a true micro system. I started with a large urn with about 20 grown-up guppies and many tiny guppies. There was a pump creating a water-feature effect. Yesterday I set it up so that the pump is now used to circulate the water to a polystyrene grow box in our plant cage which then drains back into the urn. We have a plentiful supply of pumice so I’ve filled the grow bed with pumice as the main media. The tiny tomato plants I put in are still alive. I will turn the pump off at night so the draining happens when there is no sunlight. Is that OK or should I have it on a timer and do eg a couple of hours on, 4 hours off cycles?
It sounds to me as though pumice would be ideal for the bio-filter.
Is pumice OK to use as a grow media?
audrey
Audrey……..while I have no experience of pumice, I can’t think of anything that would preclude its use as bio-filter media. It floats (at least initially) which may pose an issue for anchoring plant roots.
I’d prefer to use a timer and pump water at regular intervals rather than turn the pump off all night…..largely for the effect on aeration that it has.