Backyard Aquaponics
A place to discuss aquaponics

Hey Troutman, nope I won't be turning off the systems with trout in them - ever. Have built a fail-safe power supply to ensure there is always DO for the trout. Friendlies use tilapia that are comparatively bomb proof.

I'm using the tanks 'cause I got em. Also will be pumping the water in from deep under the tanks and then 50 metres away to the far end of the dam. This means no need for extra DO as the water movement, colder temps should do it. If I was doing it again I'd probably build cages and aerate them from under I think. But hey, I'm a novice who knows 2/5ths of stuff all.

OBO I really do admire your spaghetti/pipe factory construction skills, and your ability to move gravel mountains and dig holes, but I will play with my 'simple' water based one level IBC system for now I will keep the DO levels high to start with and play with the levels using Silvers or the Cats. I won't push it too hard though and monitor fish closely when I do it. I've allowed for a large air-stone per IBC, but suspect if I move the water fast enough having putting enough DO into the FT, I won't need to use them in the GBs.

So basically you're relying on a flow-through style for aeration... which works fine for raceway style operations.... with high volume turnover/flow through...

But, sorry, I'm not sure you can acheive similar results/flow-through... via a single pump, overflow, through sequenced IBC's...

Unless you plumb everything with 100mm piping and have a damn big pump... in which case solids removal/settling/filtration... especially in a (relatively) small IBC... IMO... becomes almost impossible...

Frankly.. for all the unknowns... and relative costs... if you're aiming to stock lightly...

Then buy a 1hp paddlewheel aerator... and just stock the dam directly... setup some of the IBC's as filter blocks... and the rest as growbeds... and just pump from the dam...

Ala... a big swimming pool or pond conversion...

P.S... if you're stocking lightly in the dam... you might not even need any filtration blocks at all... the growbeds would probably be sufficient.. especially 192 of them...

I have to say that I really like the approach of making a system that is modular and easy to replicate. But I'm with Rupe thinking that filtration here is going to be very difficult.

We definitely need more experimentation on commercial sized systems. Keep up the good work!

Two separate systems Rupe.

The dam will be lightly stocked and is just for fun - because I can. It is a very large recirculating system using the dam as a biofilter. You saw the dam and it's 12 metres deep for 1/3 of it. The recirculating dam is because I like grilled trout year round and the dam never gets above 12 degrees at 1 metre deep (currently 9.6) even when we top 35 for a week straight. It's very stable as far as temp is concerned and gets flushed every time we have 25mm or more of rain in less than 12 hours - a dozen times a year or so as it depends on existing ground moisture.

The IBC system is a small recirculating system and will definitely have air added, just how much and where is the question, but in the FTs for sure. We all know the DO requirements of fish courtesy of aquaculture, but the DO requirements of plants is less certain. That's because the parameters that work for hydroponics do not apply to DWC rafts. Plants need significantly less DO that fish, but how much less???? I will play with keeping the fish happy with DO levels and only aerate the GBs if required, but I suspect they won't need much if any. Plant DO levels are also species dependent, so much work needed here.

Tamo42, filtration could be as simple as a one half an IBC stuffed full of bird netting plus air, after an over under baffle filter in the first half. The over under baffle filters do a similar job to swirl filters and a strategically placed drain means they can be cleaned by opening a tap. Under over baffle filters create a settling area/tank. The messy bit will be the mesh or bird netting/degas area. At high stocking densities I am told it's a weekly removal and clean. So what I am trying to do with the MEO foam is have an easily removed and replaced screen filter that can be hosed and replaced.

I'll be playing with filters a lot to make them effective, cheap and easy to clean in my AP situation. The commercially available filters are designed for aquaculture and extreme stocking densities. AP can and should be different to aquaculture, we need to learn and adapt their systems - there's always a better way to do something.

The modular system means the water pump can be in any one of the IBCs and it's only the air that must be in the FT to stop the muck settling so it goes to the baffle filter/settling area and whatever follows that.

I really think this modular IBC system is a bit small for a commercial system, it sort of fits in that area between large domestic and full on farming. The beauty is that it can be started small and easily added to as funds permit and markets develop. I can see people starting with 10 IBCs a smallish water and air pump, connecting the IBCs, adding polystyrene rafts and plants and they have functioning and expandable AP system for under $2,000 (AUD). At low stocking densities or for domestic application a filter is not required - friendlies have shown this. However as the system is expanded and stocking densities go up, a filter can easily be added if/as required. Every time the owner has another $140 a an hour or so she can add another IBC raft growbed.

Earthbound says the raft channel of sheet plastic, boards/excavation and pegs is cheaper than the IBC raft equivalent, and at first glance that appears to be so, but is it? Assuming both systems start with a level site, we cost in labour and we use the UVI 100' (30 metre) size as a bench mark. With IBCs this would cost $4,200 and for another $1,800 you could add the FT's, water and air pumps and a baffle/ net filter. Add 2 days for two workers and you have a ready to go system of approx 36m2 of growing area and 33,000 litres of water volume for $7,000 - just add water fish and plants

I am sure other systems can be done cheaper if you have illegal immigrant labour, or DIY and don't cost you time, but I don't think it could be much simpler. And the commissioning price of any system is only one parameter to assess a commercial system, then there are the life-cycle costs, operating fixed and variable costs, ease of use and so on.

Also if you get a hole in the membrane of a sheet plastic system it's a real pain. This is much less likely with an IBC and if it happens you isolate and fix the problem without disturbing and draining the whole system. But the proof of the pudding will be in the eating and I won't really know if this going to work until the first run is built.

I am working on using the cut off lids of the IBCs to create the baffle filter/settling area, seems doable just have to find a glue that will stick to HDPE and be non toxic.

Michael, I'm still concerned as to filtration and DO requirements...

The UVI model is predicated on near "complete" removal of all solids and suspended matter before flow to the raft systems... hence significantly lowering BOD.. biological oxygen demand... while the rafts themselves are extensively oxygenated... and have a flow rate which I believe is significantly faster than what you might acheive by pumping through an IBC filter and subsequent IBC(s)... by overflow....

I believe that even if you acheive both the flow rate required to oxygenate the plant modules, while still managing to settle out the solids.... your maintenance may well be daily, rather thn weekly...

How many fish do you intend to stock per IBC modular system??

Even recent posts, both here and on other forums... have demonstrated the effect of stunted growth and root rot problems associated with non-aerated DWC floating raft systems...

mcfarm, Ah, I can picture it now. I'm still a bit confused on the piping you plan on having, but I can wait for pictures .

Be sure to keep us informed.

No worries John, as I said I'll be working on the filtration for a while, but the object of the exercise will be to remove all possible suspended solids which will be fed to worms in the wicking beds. So I don't see suspended solids being an issue long term, only a short term problem as I figure out the best way to effectively remove them. It may even be that after I've played with filters for a bit I decide a modified commercial rotating drum and or screen filter is the way to go - should be able to fit one in an IBC

The system will need daily monitoring obviously, but half an IBC of net filter and degas area would need emptying no more than once a week I'd guess. All depends on stocking rates and how hard I want to push a system. Not being the greedy avaricious type, I can cope with less than the highest possible production rates. It is the pursuit of maximum production at all costs that is one of our planets biggest problems, and the much loved efficiency of economic rationalists is trumped by effectiveness every time. Plants are extremely inefficient converters of sunlight to energy, but we would not exist without their effectiveness.

Plant requirements for DO vary dramatically. Obviously naturally submerged or water based leafy greens won't need much, but growing root vegetables in the rafts will be almost impossible. The trick is to tune the system for optimum production of the plant species in question. This includes getting the DO levels right. But if I move the high DO fish water fast enough through the system, having removed all the solids first, I am guessing that it might be OK. If it's not OK I'll add more air to the rafts as required. So it's not problem, just a matter of fine tuning the air/DO requirements. But my attitude is why add air if you don't have to? Better to find out what's needed and add that, rather than over or under compensate before the requirements are know.

One of the advantages of the IBC/modular system is that you can add extra air to just one tank to suit a specific plant species if needed.

Again this DO issue is a mind set problem of scaling up a domestic system that must cater for all possible species of plant. This is why flood and drain works for home users that want as much variety as possible. However a commercial system will inevitably concentrate on a few species only, and a system optimised for tomatoes won't necessarily be best for basil. And a commercial AP system optimised for rooting crops is most unlikely to be a raft system. Hell, with raft systems commercial operators are still figuring out optimum hole spacings for each plant species.

It's taken a while, but I have come to the conclusion that the simplest of small scale production systems is; AP rafts for leafy greens and some fruiting plants, and wicking beds for rooting crops and other other fruiting plants. This is what I am putting into practice too

Tamo42, their is only one 50mm return pipe from the last IBC back to the first The interconnects between IBCs are 50mm (2 inch) bulk head fittings with extra nuts and washers which is OK for a flow rate of 15,000 lph. There is enough flex in the IBC walls to allow for butting the IBCs together using only the bulk head fitting. I've tried to come up with a cheaper interconnect system that's easy to install, but haven't yet. The trick is have a firm and level floor for the IBCs which in my case is crushed blue metal road base laid over weed mat. Remembering that when full each IBC will weigh close to a metric ton.

Good luck with the design of your system. I was hoping that you would make a system similar to mine so we could compare notes but everyone's imput, no matter what the design is useful to everyone else on the forum.

One other thing, I can't remember who said it- UVI ponds are 100' long but two ponds are interconnected with a 6 inch pipe in-between them, which makes each run 200' before the water returns to the fish tanks.
Just FYI.

UVI System
Tanks 4- 10 ft Dia., Height:4 ft, 2,060 gal each Total 8,240

Clarifiers: 2- 6 ft Dia , Height : 4 ft, Depth of cone: 3.6 ft, 1,000 gal ea Total 2,000

Filter and degassing tanks: 2- 6ft x 2.5 ft x 2 ft deep, Water volume:185 gal Total 370

Hydroponic tanks: Length: 6- 100 ft x 4 ft x 16 in. deep, connected in pairs for 200 ft. runs 3,000 gal. Ea.
Total 18,000

Growing area: 2,304 ft2 (6-96x4) 12- 4’x8’ rafts ea. 72 rafts total
Sump: 1- Diameter: 4 ft, Height: 3 ft,
Water volume: 160

Base addition tank: 1- Diameter: 2 ft, Height: 3 ft, Water volume: 50

Total system water volume: 29,375 gal

Hi Angie,
My initial plans were to take over the world with giant AP systems, but this has mellowed to something more appropriate.

I guess I believe that large scale commercial AP will take care of itself, with big players moving in and building mega sites covering hundreds of hectares (2.214 acres to the hectare). I see the need to fill that niche in between the biggest domestic systems and the full on commercial farm AP units. So systems that can feed a small community rather than designed to supply the Aldis/Woolworths/Tescos/Walmarts of the world. Systems that are easily replicable, cheap to run, simple to build, and productive. Systems that the likes of transition towns would form collectives to build and operate.

That said some of my filtration experiments will included gravel beds and trickle beds as discussed much earlier, but the first filters will be mechanical. If the intermediate systems work out I might be tempted to build larger units using plastic channels along the UVI and friendly lines.

Will gladly document progress (so long as I don't drive into your neighbors letterbox and get yelled at by them every time I visit....)

I personally think it's a good idea. Each system design has it's pro's and con's. This system is really flexible, but it sacrifices some other "features", for example, this one needs daily maintenance. But it's another variant on an AP system, so I hope it works well.

There are some other features of this system that can't be done by a channel system - eg. This one can be done a previously concreted area (e.g. a basketball court or courtyard at a school), little kids can't fall in etc etc. Seems everyone's only too keen to take a dig at new ideas (constructive criticism it might be!).



The problem with this is that you've assumed it's a boolean condition - it might not be NEEDS AIR or DOESN'T NEED AIR. Sometimes this is true (TROUT ARE ALIVE, TROUT ARE DEAD - very boolean). But it might just be that it functions better with extra air. I'm pretty sure someone else on this forum noted that their channel with added air grew better than their channel without extra air. I 'spose you can work this out over time, run it with air for one crop, run it without for the next. Though you might end up with a nasty condition of TROUT ARE DEAD.



Yeh - I'm pretty sure my latest disaster was simply me overfeeding, and it building up and up and up and eventually consuming all the O2 I was putting in (though I'm not sold on this). So I reckon solids removal is going to be pretty important for this too. The baffle/shade cloth system sounds great, but a lot of maintenance. DuffLight operates a pool system and swears by his swirl filter - I can't see why you couldn't fit one into your system between the fish tanks and the growbeds. To make it more modular, you could just run it separately (with it's own pump, so you can "drop it in" for a day to remove the solids from a particular tank in the run). Might end up being less maintenance than the filter if you have to wash out every day (what happens if you go away for the weekend?!).

The proof is in the pudding, just do it and we'll all look forward to seeing the results.

Only one correction Simon, I'll only play with DO requirements with the plants - they're much more forgiving than dead fish. So no boolean logic, as plants will wilt a bit and then recover if the DO levels are subsequently raised.

And my neighbour is cool, he was just having a bad day - he's an investment banker type and the GFC is still giving him grief from time to time. Apparently it's not good when you lose a few billion dollars to bad debt write downs

I guess there have been a lot of wild claims flung about, both here and on other forums. Systems that will save the world, systems that are hugely productive and only a few dollars to construct. Systems that are better than all other systems!!!! Yet many of these either flopped or were never even built.

As many people will understand, when you start to build a system from concept, it can very quickly and easily blow out because of unforeseen costs and materials. And also just as easily there can be unforeseen problems with the design or operation of a system.

Personally I'd rather people tell me about potential problems I might find rather than be quiet about things just to save my ego...

For instance, if someone said to me, "look at those huge gum trees right next to where you're building your system, they will be a problem, might want to get rid of them or cover your system." And if someone had said to me, "That swirl separator you're looking at using won't work decently, you need more angle in the base to get your solids out better."

But then perhaps I wouldn't have listened and just done things anyway....

Oh, and of course you can build a raceway straight on top of a hard surface like concrete or asphalt... I wish the area we built ours on was a solid surface like that, it would have been easier with less site works..

I understand that critiquing a design is essential (I'm an engineer - it's my job!), but sometimes there is a lot of critiquing without much encouragement. I can see that this works, but I don't want to see it turn people off innovating because I feel that's what we're all about here! A bit of self discovery, applying stuff from other domains to ours, and innovating stuff fresh. Communication courses say critiquing should be done in a "sandwich" style - "I like the idea, have you thought about XYZ?, it's certainly a different angle". Anyway, lets drop it and get on with the critiquing.


Hehe - Michael I'm sure he's a lovely guy, but he sure as hell had a go at me (and I wasn't even driving!).



Yeh I guess you can do the channel on concrete eh. Didn't think real hard about that one.



But if it's one system, which is circulating, you really don't want that DO depleted water from the end of your run being pumped into your fish tank (assuming it is DO depleted). I've no idea how long it takes for O2 to actually get into water (anyone actually know?), but maybe that's something you need to consider.