Backyard Aquaponics
A place to discuss aquaponics

It can take upto six weeks or more, depending on water temps.

But the rest is incorrect.

There are two main ways to cycle: fishless, or with fish

In the first case you add controlled amounts of ammonia source. E.g. Carlie carp, clear ammonia, humonia (aged urine), urea. And monitor your levels until you see the ammonia, then nitrite peak and drop, followed by "sky rocket" of nitrates. You then add fish.

This approach has advantage in that you don't risk the fish, and is highly controlled.

The second way is to add a couple of small or sacrificial fish, feed them lightly, then again watch your levels. This can be slightly more difficult to control and you may need to slowly ramp up ur fish numbers to get a good cycle.

Do a search for fishless cycling on the forum search.

As far as plants go....you can stick them in anytime and supplement with seasol (seaweed emulsion) etc until the fish are producing enough load to supply sufficient amounts on nitrates.

Hello mates, sorry to labour a point but given my hypothetical GB of 2mx1.30mx0.3m what would be the 'minimum' number of fish I would need to run a flood and drain bed of lettuce.

Do any of you guys use the nutrient flow system as part of your aquaponic set up, I mean the pipes with holes cut in them for lettuce?

This might give you some ideas Anthony...

viewtopic.php?p=348472#p348472

wow fantastic, just out of interest how many fish are supporting that lot, and what ratio fish to filter bed do you use?(if its not impertinent to ask).

Also does anyone know whether dutch buckets filled with medim work as good filters i.e. suitable enviroments for the bacteria, could I use a ratio of one bucket per fish?

As a general guide Anthony... we equate 20-25 fish for each 500L of media....

So your one grow bed of the dimensions you gave could support 20-25 fish...

I'd err on the side of caution with a new system.... and you jsut don't need a lot of fish to grow plants anyway...

I think I ended up with about 25 - 30 fish powering the system in the thread...

I've posted another system... that has 6 grow beds of the same size.... powered by 100 fish...

Good morning Rupert of OZ, I have assumed right from the beginning that the filtering that is needed to clean up the water for the fish and convert the amonia to nutrients is obtained exclusively from media filled grow beds. Does your extensive tube/flow system contribute in a significant way?

Essentially no... the NFT channels, or DWc rafts for that matter.... don't provide any significant nitrification...

But in fact DWC raft beds... and NFT... both require solids pre-filtering... otherwise any soilds adhere to the roots... and cause root rot....

Which means... in home, or small hobby farm systems... you must employ some solids removal filtration....

Most do so.. by using grow beds.... some by external soldis filtration... swirl filters... radial flow filters... or other filters...

As scale increases... particular with higher stocking densities.. you start to move into aquaculture style filters.. moving bed bio-filters... drum filters etc....

And so you should.. if progressing to a "commercial" system... particularly if optimising the fish part of the "aquaponics"...

The only other alternative... is to remain with low stocking densities... and the "friendlies" DWC raft model is one such...

Using media beds... "hybrid" systems... with raised stocking levels... is just a nonsense model... that defies all very well research aquaculture principles... and is potentially disasterous in my opinion...

You might get away with for a while... but eventually... it'll either compromise/kill your fish... or meddle with your water parameters... to the point where your plant stocks begin to have pthium and other issues... a commercial disaster...

The current "hybrid" model being hawked around... has been slapped together from backyard pieces.. and backyard knowledge... by a backyarder....

The idea that it represents a successful modular "model"... is IMO... unfounded... and unproven... to show any commercial value...

The idea that questions of scale... can be overcome... by duplicating an "unprofitable".. unproven module... is jsut as questionable...

If the module is unprofitable.. and/or flawed... duplicating it xxx times... just means you end up with xxx number of unprofitable/flawed modules...

Rupert of OZ, once again thanks, how long do your lettuce take to grow? I was told you could harvest after 1 month and what about your tomatoes?

Does the height of my pump have any bearing on things?

How hot does it get where you are? is water tempreture in the tubes an issue?

I apologize for the barrage of questions but this is going to be a significant investment for me as we will have to buy everything new, there is nothing left about long enough here to scrounge.

sorry the question should have been what is the optimum height for the sump.

Lettuce will take 4-6 weeks (from seedling)... depending on environment/season...

Temperature transfer from NFT can be issue... depending on channel length, number of channels, flow rates, temperature etc...

As most fish prefer warmer water for growth... the heat transfer can be beneficial....

Head height will determine your flow rate... as far as a sump goes, there's no optimum "height".... the sump needs to be below the height of the grow beds/NFT.... and be able to hold the volume of water that might drain to it if the pump(s) were off....

Shallower sumps/tanks... and/or smaller volumes of water.... heat and cool quicker...

Hello Rupert of Oz, thanks for your useful info. We are going to incorporate flow beds as well as 1 or 2 medium sized flood and drain beds backed up by Dutch buckets. this will be with 250lt fish tank and about 25 tilapia does that sound ok for starters?
When you filter the solids is there still enough nutrients to feed the plants? or do you have to add something extra? we have built a swirl filter that is very efficient and I'm worried that the water is to clean.
Is it very hot where you are? how do your lettuce like the heat?

Hello can anyone tell me whether filtering out the solids depletes the nutrient levels? (or is that a really stupid question?)

Also we have been runnuing our test system hydroponically to iron out any glitches before we introduce the tilapia, our lettuces are 2 weeks old and are bolting already; anyone have any idea why?

What is your temperature?