Bell siphon question

[Ryan B]

I have set up a small system to work out the bugs of a bell siphon in a flood and drain system. It is up and running(water only), and has been faithfully doing cycles for 3 weeks now without issue. My problem is I have the 2 containers seperated by quite a distance to get the volume of water in the drain tube needed to fully siphon down the grow bed(in a short time). I want to make a very compact system with the grow bed stacked on the fish tank, and am having trouble working this out. Any ideas?

I have considered using the float valve mechinism for a toilet, as it shoud accomplish the same thing in a compact space. Any drawback to this type of set-up?

Thanks,

Ryan

[Jonathan Dyer]

Sorry Ryan but how about a continuous trickle flow system such as mine. It makes do with all the setbacks of flood and drain and what you are currently encountering is a good example; in a way is retarded proof. Why do people try to over engineer something when making it simpler is the answer.

[Ryan B]

I built the bell siphon because its function is quite interesting. Although I agree with the keep it simple approach, I also want to build something that has a high "coolness factor". Even though an aquaponics system has that by itself, something as neat as the action of a bell siphon would add to that.

[Murray]

Hi Ryan,
As the distance increases the time to siphon will be longer, and that is not a problem for the plants anyway.
It is just a matter of balancing the outlet size with the water inflow.
I am facing a similar problem right now, I am making a tub to grow a pawpaw tree in, and I want to use a bell siphon, because they are just great, but it will take up too much room in the tub, so I am opting for a tube siphon nicely attached to the outside of the tub.
I totally agree with you, bell siphons are amazingly simple and work really well.

[Outbackozzie]

I have 1 system that runs on siphons (18 of them), and 1 that runs on continuous flow, there is no difference in growth between the two systems.

The new 1000 litre beds that I am adding to my big system will be trickle in the top, drain out the bottom.

I agree that syphons are cool, but the only advantage to them is the drawing of oxygen into the root zone while rapidly draining.

[Hamish]

I have 1 system that runs on siphons (18 of them), and 1 that runs on continuous flow, there is no difference in growth between the two systems.

The new 1000 litre beds that I am adding to my big system will be trickle in the top, drain out the bottom.

I agree that syphons are cool, but the only advantage to them is the drawing of oxygen into the root zone while rapidly draining.
The other good thing about a flood and drain system over a continuous system is that all the gravel will get wet equally without the need for a water distribution halo. I feel the flood and drain systems might have benefits distributing the fish waste throughout the bed creating beter nitrification.

[Murray]

You are right Hamish. The difference between the two would become more apparent over time.

[Outbackozzie]

Worms distribute the 'solids' quite well.

I find that a halo is a lot more reilable than a syphon. If you do anything like adding more beds, change the pump to a different type etc, it stuffs up the siphons, and you have to fiddle for ages to tune them right again. Cont flow just keeps on keepin on.

[GaryD]

I feel the flood and drain systems might have benefits distributing the fish waste throughout the bed creating beter nitrification.


Worms distribute the 'solids' quite well.

And the best situation of all is to keep the solids out of the beds in the first place. This bit about the role of worms and solids in grow beds is an enduring myth that is not supported by science.

Fact: Biological filters function most effectively (in a nitrification context) when solid wastes are excluded. This is not aquaponic lore here; but rather well-established wastewater treatment science.

The argument in favour of having solids in beds has it that the worms mineralise the solids making them available for the plants. The argument continues that the reason that people can grow fruiting plants in AP systems (as distinct from just leafy plants) is because of the nutrients that the worms liberate in process the solid waste.

This argument doesn't stack up because, if we look at the UVI model, they do pretty much whatever they can to remove solids.....and yet they still grow tomatoes, cucumbers and capsicums in addition to lettuce and herbs.

Heterotrophic bacteria break down the solids and convert them to ammonia from which nitrifying bacteria then convert them to nitrites and eventually into nitrites.

In any case, any mineralisation of the solids that need involve worms would be more effectively done outside of the grow beds.....and could still involve the use of worms. Any worthwhile thing in the converted solids could then be added back into the system by way of worm tea.

Gary

[Hamish]

Heterotrophic bacteria break down the solids and convert them to ammonia from which nitrifying bacteria then convert them to nitrites and eventually into nitrites.

I know this is just a typo but...

Heterotrophic bacteria break down the solids and convert them to ammonia from which nitrifying bacteria then convert them to nitrites and eventually into NITRATES

Feel free to delete my post - just wanted to make sure this didnt stay in the thread if it was not what you meant...

[Outbackozzie]

Gary, you seem to be talking about maximum production commercial systems, for normal backyard sort of use, 'solids' are not going to be a big concern.

If all this trouble is going to be taken for removing these so troublesome 'solids' from the water - why use fish at all, surely hydroponic's would make more sense.

I dont use worms to make it possible to grow flowering fruits/vegetables - I know they grow in AP without worms, seasol does the same job. The worms are there to consume waste in the beds only, the nutrients are an added bonus - the worms do the 'solids' removal, without the trouble of maintaining yet another filter.

[DaveOponic]

Can someone please post a photo of a "bell siphon". I've been trying to follow the discussion here but I'm not sure what the siphon is in the AP system. I gather that it is to get the water into the grow bed. I just use a PVC pipe in a rectanglular loop with small holes drilled in it every few cm. (Is this what you mean by "halo") When I eventually make a bigger grow bed I will probably use flood and drain. At the moment my small growbed sprays water for 15 minutes and then off for an hour. In the hot humid tropics it seems to work OK.

Dave

[Murray]

Hi Dave,
Here are three pix that may help.

Pix # 3 shows the fixed upstand made from 25mm pvc pipe with the "Bell" about to go down onto the fixed upstand
Pix # 2 shows the "Bell" in place over the fixed upstand
Pix # 1 shows the outer going over the bell siphon. The outer is to keep the gravel or other media away from the bell siphon assembly. When I took these pix we had not yet drilled weep holes in the outer.

I hope this helps.

[DaveOponic]

Thanks Murray.... I'm still not clear on the purpose of it. Obviously more than a strainer to stop gravel etc. entering the pipe. Is it to aerate or allow water to enter the pipe more slowly?

Dave

[Murray]

The purpose of a bell siphon is to facilitate flood and drain cycle while having a constant flow of water into the grow bed.
A relatively small pump can be used in this kind of system.
The water is pumped into the grow bed and the grow bed will fill up to the top of the inner stand pipe. The water will then commence to flow over the top and down into the standpipe. As the standpipe is covered with an outer pipe or cap, the increasing water flow down the inner standpipe soon forms a siphon.

The water in the grow bed is quickly evacuated down to the bottom of the outer "Bell" which has a small bore plastic pipe attached to the side of the bell and enters the top of the bell. This allows air to enter the bell when the water level reaches the bottom of this small bore pipe thus breaking the siphon.

The constant flow pump continues to deliver water to the grow bed. And so the cycle continues.

A very effective method of creating a flood and drain cycle in a grow bed using a constant flow pump.

[Hamish]

They really are brilliant - they just keep on working.

[DaveOponic]

OK, now I get it. So no need for any timer? I will have to try this when I make my new growbeds.

Just a further question... what is to stop the thin tube from becoming blocked up? In the two grow beds I have made so far, I have used a stainless steel strainer over the end of the drain pipe so that it doesn't get blocked up. Occasionally when I have noticed a reduced flow, i put the garden hose on the end and unblock it, this seems to do the trick.

I can see I will have to experiment with the plumbing before I fill up my big growbed with gravel

[Jonathan Dyer]

I feel the flood and drain systems might have benefits distributing the fish waste throughout the bed creating beter nitrification.

I see no evidence in this and agree too with everything Garry said.


Gary, you seem to be talking about maximum production commercial systems, for normal backyard sort of use, 'solids' are not going to be a big concern.
If all this trouble is going to be taken for removing these so troublesome 'solids' from the water - why use fish at all, surely hydroponic's would make more sense.

Yeah, but even the backyard system can have a commercial foundation seems that the flood and drain system widely used by most people was copied off S & S Aqua Farm’s “Bioponics” technique. What is so wrong with trying to maximise a system to grow more fish and plants in the same amount of water for a similar cost? Removing solid wastes is an important factor in this process. Sure hydroponics is great (sorry to say if not better) but I think people like the idea of being able to produce one product that goes to fuel the next and so forth. I am frequently trying to make my system better at filtration and the removal of solids (my air lift is working great) but still I am not getting crystal clear water. Ozzie I know you realise this but what is wrong with trying to match yourself up with the commercial guys, they are commercial for one reason they started off in their backyard and expanded from there making as many improvements as they saw necessary and now years later they are successful at what they do.
I agree continuous systems just keep on going and going, I have not had any problem yet, I would also agree that there would be hardly any growth difference between the two systems.

[Murray]

The flood and drain way of doing things does originate with S & S Aqua Farm’s “Bioponics” , at least in modern times anyway.
It is also true that Hydroponics and Aquaponics will yield very similar quantity/quality of a given crop of veggies with slight variations. (Fish are yet to be produced in a Hydroponics system.)

But most folk (home systems) want to do Aquaponics because of the beauty of the synergy of plants and fish. The convenience and simplicity are just amazing.

We don't have to go out and spend a fortune on various nutrient blends.
We don't have to run water to waste.
We don't have to scrub out our equipment after every crop for fear of disease.
We don't have to have elaborate waste/solids removal systems.
We do get two crops for the work and cost of one.
We do get chemical free veggies and fish.
We do get a good return on capital outlay.
We do get a good crop in a minimum of space
We do have the most efficient use of water.

For the home system the simplicity and reliability of the S & S Aqua Farm’s “Bioponics” model is unbeatable......I believe.
Having said that, there are successful variants to the S & S model.

Commercial systems have different requirements.
Mass plantings into gravel grow beds is just not practical from a labour point of view.
There are basically two practical ways to do Aquaponics commercially
DWC or NFT. There are variations, for example Auto pots etc, but DWC and NFT are by far the most used and have good track records. Systems like Auto Pots work well but generally are thought to be too expensive to be popular.
Most systems like Auto pots have emerged from the Hydroponic school of thought and assume the use of water that would otherwise have be run to waste.

But for proven practical commercial applications DWC and NFT are the choices for true recirculating systems.
Both systems require the solids to be removed prior to the nutrient rich water entering the troughs or channels.

Some folk see Aquaponics as Hydroponics but with fish water instead of manufactured nutrient blends. This usually means that they intend to run water to waste. They see that pesticides and artificial fertilisers can be added downstream from the fish tank if needed or desired.

Some folk see Aquaponics as Aquaculture with the added advantage that the downstream water can be used to produce a crop. Examples of this are Barramundi Blue.

Some folk see Aquaponics as what it is, a separate system of its own with its own distinct identity and advantages. To be seen as a whole, complete, symbiotic system.
I believe that Aquaponics will emerge as a principal food production method because of what it is and the many advantages it delivers above Hydroponics and Aquaculture by themselves.

[Tomer]

Hi Murray
as one who's system is still under construction, i have a layman's queston: i am deliberating the idea of having water pumped from the fish tank (floats & Timers probably) to the gravel or other medium grow beds. these beds will function as solid removers and, well, growbeds. the water will drain to a sump which will function as a dwc (which means the sump will be larger than required and never fully drain) being topped with styrofoam boards for growing greens and retaining water heat. a certian amount of water from this sump cum pond will be pumped back to the fish tank..
does this sound like a reasonable setup? i'm sure i'm not inventing anything new here, but it would be good to hear the pro's and cons.

[Murray]

Hi Tomer

Yes that will work. There will still be some nitrates in the water when it arrives back at the sump.

[Tomer]

The purpose of a bell siphon is to facilitate flood and drain cycle while having a constant flow of water into the grow bed.
A relatively small pump can be used in this kind of system.
The water is pumped into the grow bed and the grow bed will fill up to the top of the inner stand pipe. The water will then commence to flow over the top and down into the standpipe. As the standpipe is covered with an outer pipe or cap, the increasing water flow down the inner standpipe soon forms a siphon.

The water in the grow bed is quickly evacuated down to the bottom of the outer "Bell" which has a small bore plastic pipe attached to the side of the bell and enters the top of the bell. This allows air to enter the bell when the water level reaches the bottom of this small bore pipe thus breaking the siphon.

The constant flow pump continues to deliver water to the grow bed. And so the cycle continues.

A very effective method of creating a flood and drain cycle in a grow bed using a constant flow pump.

Hi Murray
there are a couple of things i can't grasp - first, is there always some water on the bottom of the grow bed inbetween cycles (the small bore pipe doesn't seem to reach the bottom)? and second - the drainage from the standpipe - does it have to be in a slightly negative angle (to trap air to facilitate the siphon) or a regular gravity flow down to the sump?

[Murray]

Yes, there is always about 25mm of water left in the bottom of the grow bed.
A small upturn at the outlet of the siphon can sometimes assist in starting the siphon....create a bit of back pressure. It is really more about regulating the inflow of water in relation to the size of the standpipe. You need a tap on the inflow from the pump. Too much inflow and the siphon will start very easily, but may not want to stop. Too little and it may not start...it will just dribble.
I hope this helps.

Murray

[Tomer]

Hi Murray
thanx. that answers my questions perfectly.

[GreenCow]

Hi Murray,
What is the best size for the standpipe and does the air break need to be below the top of the standpipe opening? I have been attempting to set up a bell siphon with a 2" standpipe, but it doesn't seem to start up very well. I think the standpipe is too large and it does not have enough water to fill the pipe and start a good flow. Any info you are willing to pass on about the design of one of these guys?