Backyard Aquaponics
A place to discuss aquaponics

Greetings, I know that the Bell Siphon is the most common of automatic siphons used in aquaponics but it is also quite complicated. I was wondering what the objection to using something like an overflow siphon is? Now to be clear I am not talking about a Solids Lift Overflow



but rather a normal overflow siphon. The main difference is that the siphon has an elbow in the top rather than a tee. Certainly that would not be advisable in the fish tank because if it engages, it will empty the tank; which might annoy the fish. However in a grow bed that kind of a siphon would be fine as it would empty the grow bed until the bottom intake tube started pulling in Air.

So what I am wondering is what the problem with the much simpler overflow siphon. Is there a problem with root invasion since the water doesn't go up first before going down? Is there some other issue that makes it a problem?

I was considering in some buckets for putting in a simple overflow siphon with a gravel guard around the bottom of the siphon tube. The plumbing would be very simple compared to a bell siphon, especially in the constrained space of a bucket.

Any experiences with this?

Hi Kraythe, would you be able to provide a diagram of an overflow siphon? I don't know what it is.

Also just a question - why do you feel that a bell siphon is complicated? It has not moving parts and basically consists of three vertical pipes (one being the media guard) and an end-cap on one of them.

Thanks.

Regards, Martin.

I'll agree with Martin, a bell siphon is easy enough to make. I wouldn't call it complicated.

The overflow would work, but I'd imagine you'd need a higher rate of flow for it to kick off, ie, the entire higher pipe would need to be covered with water for the siphon to push the air out and kick off, otherwise it'd just trickle out and not kick off like a normal siphon.

And with the higher flow, I think it'd have issues breaking the siphon as well, so it'd continue to gurgle.

I haven't done it myself though, so I'm curious to see it it'd work.

Its just like an solids lift overflow (which is a siphon) except the top is an elbow, not a T. Think of it like a big upside down U going through the wall of the tank. Where it goes through is your water level and the outside leg needs to be longer than the inside leg to work. Once water gets above the top of the inverted U the outside leg fills with water and starts the siphon.



As for the bell siphon, its not so much complicated, built dozens of them, but it takes up a lot of space if you are trying to do a bucket based system such as I am helping a friend with. I can put a siphon in all the buckets but it takes out at least 2.5" section of every bucket and that is not optimal.

Hi Kraythe, Now I see what you're referring to. I have seen them referred to as external siphons. They're just as effective as normal bell siphons from what I have seen. Most people don't use them in AP as space considerations aren't as critical in a large grow bed as it is in a bucket. There are definitely members here using the external siphons and they seem to work fine. The only person I have seen complaining about them was someone that did not build them properly. They built the outside with soft tubing that distorted and made it hard for the siphon to start and stop. If it's what you feel comfortable with I don't see a reason not to use them taking into consideration the issues you mentioned earlier.

Regards, Martin.

Hi Kraythe,

The syphon you have described will work and others have used them in the past. There are a few issues with this configurations. The only way it would be more space friendly is if you are suggesting using it without a media guard, and there lays one problem because cleaning roots away from the pipe is impossible without digging it all out. So blocking can be an issue.

If you use a small media guard with this set up the design of the guard is difficult because of the pipe running through the side of the bucket and you risk media falling into the cavity in blocking the pipe. If you put a screen on the end of the pipe once again you have blocking issues and difficulty to clean.

Lastly, having the suction end facing down to the bottom it will want to draw all the settled wastes from the bottom where they should stay for mineralisation and not be drawn back to the FT or ST.

So yes it can work but it is not ideal. The standpipe design (through the bottom and facing up) is the absolute best way to set up a GB, all the trials and tests were done and confirmed a long time ago.

A loop syphon would be a better option in this instance because they work well for small pipes.

The only issue is that I am not too keen on using a bell siphon in every bucket because of the amount of them I would need to build and maintain and the space they will take up in a 5 gallon bucket. Another idea that I had was to link 5 or 10 buckets together with taps in the side so that they all essentially form one grow bed with the bell siphon in only one of the buckets.

Another problem I had in the bell siphon is the structural support of the siphon going through the bottom. The plastic is quite flimsy and the siphon doesn't have anything to really grab onto making it difficult to mount, not to mention difficult to move the buckets around.

So what about the taps on each bucket? Anyone tried anything like that? The idea is that each bucket has a 3/4" tap in the side very low. Outside the bucket there is a T fitting into a common 1 1/4" pipe that carries the water to a common single bell siphon either in an additional bucket or all by itself in a simple pipe assembly. none of it would be glued because there would be no significant water pressure. then you could take it apart by separating the t fitting and then cleaning roots from the drain.

No I wouldn't put a bell in each bucket. You could make them CF or go with loop syphons, Im not sure what buckets you are thinking of but a cheap 5gal bucket could be a very flimsy container to use, I wouldn't think they wouldn't last long in the weather either. Ive used heavy duty 5gal buckets as wicking buckets and they worked fairly well. Fish&Food has made some good wicking pots that are all tied in together.

I think auto pots is another way, they work via a drip system I think, you could try searching them here on the forum as Ive seen them here.

It seems the problem is lots of small GB, this is a common issue.

the solution is less but larger GB's!

even piping the buckets together with one common siphon will have issues, ie uneven flow rates and blocked drains.

But it is probably doable.

I like Charlie's idea of using a CF system.

Hi Kraythe are you choosing to use 5gallon buckets due to space or budget constraints? If you have the space and budget you might want to opt for full size grow beds. If you're from a hydroponics background it might seem natural to use buckets but with the recirculation flow in AP the bigger grow beds are more efficient.

Regards, Martin.

For an external Syphon loops are the cheapest and easiest; EB had, in the early days a large number of half cut blue barrel GB's on loops.
For a multiple GB dump I would go a Flout.
As Charlie said, and I tried to tell you before you have to design a system to provide easy access to your draining point; its all very well to have a theoretical idea of water flows etc but when it involves multiple variables err on the cautious side.
This is only imho BTW I am not into telling people what they have to do.

All good points guys.

I think you should employ a little man with a lever and every time the bucket is full he pushes it down to drain the bucket and when it is empty he lifts it so that it fills again. He should be strong so his arms don't get tired.

I have used bell siphons in the past but eventually between roots, debri and solids buildup in my input line, it always seems to require some occasional tinkering to keep it working. I usually end up getting tired of it and just using constant flow.

I tried something new in my ferro bed and it is basically a modification of this overflow siphon design. It's been working like a champ for a little over a month, i guess it's time i update my thread, i will take some picks and post them later today. I find it more reliable than bell siphon, it took almost no tinkering to get it working and by my calcs it's cheaper than loop siphon components.

I made an overflow siphon, mainly because i could not access the bottom of the GB easily.

A large bucket with slots made do as a media guard, 2 - 19mm poly pipes sealed through wall drained the 700L GB with gravel in about 5 minutes.

worked pretty good but once the poly got blocked by roots , was easy to fix via bucket.

unfortunately the GB had more leaks than Julian Assange