Backyard Aquaponics
A place to discuss aquaponics

Hi All,

Firstly I would like to thank the people involved in the several hundreds of posts I have read over the past few months to generate my interest in Aquaponics. I was looking for something fun for the family to do in the evenings together and my young children love fish. We are based in Point Cook in Melbourne, Victoria.

So against some peoples posts I decided on a continuous flow system that feed from the bottom up and after some testing and modifications have a working system that pumps about 850L an hour.

1 x Fishtank
Nally Megabin 780L
Clear Pond Infiniti 4200 Pump - External Fully Encapsulated Pump (Overheating Protecting/Minimal Maintenance/Adjustable Flow Rate)
PondOne Claritec 5000UV filter

2 x Grow Beds
Nally Megabin 780L (2)
Water input from the bottom 25mm and 3 x 25mm out to the fishtank. Water flows out from GB at 859L hour.
50% gravel (20-40mm) in the bottom & 50% clay pebbles top as these bins are deep.
The flowing water is about 50mm or so under the top of the clay pebbles.

I have included some pictures and you can see 3 unused bins which i will plumb soon, but wanted to run the other 3 first to make sure everything was working ok.

I have started cycling using the fishless cycle method and hope to have it sorted after xmas so I can get some fish in as soon as possible. The plants seem to be doing well and the tests seem to be good.

Thanks again and if you have any advice or tips please feel free to send them through.

-J.

Wow, what an interesting system J...

Welcome to the forum...

thanks admin the water colour has cleared up heaps since the photos were taken, its very clear.

Hi J... welcome...

So are the Nally grow bed tanks completely filled with hydroton???

And why/what made you decide to pump/fill from the bottom??

50% gravel (20-40mm) & 50% clay pellets, the water sits about 50mm or so from the top.

I chose to pump from the bottom because I read a lot of comments that said their was areas of low nutrients. dry areas within the bed and blockages at the outflow when doing continuous flow from the top.

I saw the end of a program on foxtel a few months back (not about aquaponics, but more of a horticulture program) and saw the benefits of pumping up with oxygen flowing through all the roots and also wont have issue of bed waste sucked to the bottom blocking the outflow. with 850L an hour I have good flow and the outflow from the beds seems to be evenly spread so I expect that their isn't any major nutrient dead spots.

When I first pumped water through it the dirt from the gravel came up with the water and you could see the flow through the colour and it looked fairly good. I think it works because the gravel is so deep it has a chance to hit all the different shaped surfaces of the gravel and bend through the bed before it gets to the roots causing it to spread evenly, not sure but theory seems possible on that.

Either way, its my little attempt and hopefully it proves successful. At worst i can swap it around or go to flood and drain scenario if need be, hence why i haven't duplicated it with the other tubs yet.

Hi TQ - love it!

Can you link to where this was quoted...



I don't quite follow the bit about "pumping up with oxygen flowing through all the roots"... as one of the principle benefits of "flood & drain" is the additional oxygenation of the water as air is drawn down through the media (and subsequently into the water)...

Constant flood relies on the water being oxygenated within the fish tank, and/or by water return... your system seems to rely totally on just a constant "overflow" from the grow bed to the tank...

I think you'll need to aerate the fish tank really well.. especially as the depth and volume of the water could result in the water warming signifcantly during summer..

And I'm really intrigued as to where you heard this from...



One of the benefits of the grow beds... is that they not only act as the bio-filter... and perform nitrification... act as solids filtration, and by action of the worms, mineralisation...

I've not heard of any systems, timed standpipe, or siphon... sucking wastes "to the bottom blocking the outflow"... or of any "major nutrient dead spots"...

I'm actually concerned that your design may result in a continual, and increasing.. level of suspended solids..

Thanks for your feedback RoO,

I decided on a continuous flow system before making my design as this was my first attempt and was much easier to design and deploy imo. I have read many websites over the internet on this topic CF vs F&D and even this link on backyard aquaponics briefly mentions weaknesses in continuous flow/flood systems (Obviously their were numerous posts as well )

http://www.backyardaquaponics.com/compo ... signs.html

If I flooded from the top my understanding is you risk the water not evenly spreading through bed and there has been plenty of reports in plenty of forums of blockages in beds. My problem was that because my beds are so deep I had to fill with gravel 50% meaning if I got a blockage I would have to more than likely remove just over a cubic metre of gravel and clay pellets to fix it. Because I pump from the bottom the pressure is quiet good to prevent it happening and the top can block in theory but I can dig 50mm down and clear it if it ever did block. My understanding is my bed will still work as a biofilter and the solids filtration I think will be quiet good given the size of the bed, mixed fill and filter. In theory I could actually backwash the setup anyway I guess if it did become a problem.

I have an aerator with battery backup ready but haven't decided to use it yet as the outflow seems to break up the surface tension of the tank fairly well and appears to oxygenate the water well, but proof will be in the plant growth and fish behaviour i guess. Given I am still cycling and waiting on the plant life to take off, I guess I will make a decision in the coming weeks. I have read several articles and posts on this exact topic no-one ever agrees, hence why I bought the aerator to begin with but prefer not to have to use it to keep operating costs down and prefer to use it as a power out aerator.

I have concerns that the water is going to be too cold and well keep an eye on this over the next 6 weeks. The FT/GB (nally megabins) seem to be insulated quite well and the lid on the tank seems to keep it very dark and cool. The double plastic on most of the surface area of the megabins seems to be insulating but bit hard to tell, but i'm now collecting data on temperature with my cycling data so hope it will give me an idea before I stock the tank. I also live on the lake so will be able to compare the water temperature as well with the surrounding waters. It seems to be staying too cold and I understand this may make the cycling process take longer?

Ill post some more info in the coming weeks to let you know how it goes. Its a bit of fun and if I have to go flood and drain it is fairly basic mod from what i can tell.

i thought i could run a system without aeration because there seemed to be heaps of water movement from the returns.
the fish were heaps better(not dying and eating more food) when i added heaps of aeration into the system.
Especially when i stocked with trout
Byron

I wanted to use tanks similar to those, but couldn't find them cheap enough.
Nice clean system you have there. It looks very professional.
My idea with using those tanks, was to have the fish in them, and to be able to make it modular, ie fork another on top that overflowed in to the bottom one. Also you can get 2x1 profiles, so the FT could sit atop the GB.
It looks very pretty.
I'm mildly concerned about constant flow systems, filling from the bottom, as you may find it hard to germinate seeds, being as the upper layers may never get wet.
I'd almost recommend using a different material on the top that might 'wick up' some of that moisture.
But see how you go, and wait until you've killed a few fish, every system is different, and killing some fish is pretty much inevitable.
upgrading this system to slow drain would be simple, just choke the drain and put a timer on your pump.
Keep us posted, and let us know when you'll be hosting the next Victorian BYAP meet

Most of the reports of "blockages", or uneven distribution of water through the beds... relate to systems that only have a single inlet point to the grow bed...

The link above suggests, and I highly recommend.. a "halo" distribution of water around the beds...

There are others, usually confined to a few on a particular forum... that suggest that grow beds "clog up" and require regular/annual cleaning...

But few have found this to actually be the case... and those that have... have inevitably been under-filtered in relation to the number of fish stocked, and the level of feed....

Regardless... much of the aeration of other styles of systems... is the result of oxygen/air being drawn down through the media... and/or the water return back to the fish tank from the grow beds....

Even then I advise having external aeration...

You have neither, or at least very limited aeration from return from the grow bed... and none if pumping stops....

IMO... both your cycling, and future plant & fish health... would be greatly improved by putting the aerator in place... and turning it on...

Aerator it is then! I appreciate the feedback.

I chose the clay pellets because they seem to draw up the moisture through them, and checked today and under the first 1 or 2 pellets their was moisture, wasn't flooded (about 50mm lower) which is good to prevent root damage I'm told, but definitely moisture. I have put seedlings in and sprinkled seeds amongst them as I read the time the seedlings grow the seeds should germinate and come up after, so will be interesting to see how they go, I also hope the roots play a small part in attracting the moisture up, but i'm no expert so guess I will soon tell but thanks for the heads up. Another thing to look out for!

We move every few years for work so having them in pallet bins means a forklift can drop them on a truck and take them with me.

Thanks fishman for the help today with sourcing a few things. Will let you know how things go.

looks like an interesting setup what area of vic are you in