Backyard Aquaponics
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I'm currently in the process of setting up a new system. I'm using a 275 gal IBC container with 4 half barrels and a 4' x 4' x 7" flood table that tend to use as a floating raft system I have a 55 gallon barrel partially buried in the ground below my half barrels GB so the will drain into it, I have a 1000 gallon per hour pump that will return the water back to the FT.My setup is a CHIFT & PIST. I also plan on adding a 55 gallon Bio filter setup to the system in the future. My question right now has to do with the Bell Siphon setup. I've read many different threads on this subject. I've designed 2 different bell siphons one with a line coming from the top and zip tied to the side just above the bottom of the bell and the other without utilizing a 1 & 1/2" standpipe to a 2" wide mouth with a 3" dia Bell, I'm still having a problem with the breaking of the siphon on both designs. I also have to put some kind of weight on top of the bells to get the siphon to start, Is this normal? Is it because of the curved bottom of the barrels? How does the flow rate affect the bell siphons? I do have ball valves on the feeds. I'm trying to get them working without putting in the Hydrton in GB but this also seems like the grow media will take up a lot of the volume and will effect the flow rate also. Any help I would appreciate.

Post some pictures - might be easier to help. I have read of others having trouble with syphons in blue barrels, but do not know the details/

I used Affnan's design and it fired for me first time and has not missed a beat sense....mine is in the top of an IBC though.

You might investigate too high flow rate first, this seems likely to affect both. You have a high flow pump there...
A 1-inch gap from the standpipe top to the cap is recommended. If the air under the cap makes it float up, there is too much gap for the rising water to fill. It's more what happens at the top than anything at the bottom. Yes, weigh them down and find a way to keep them at the level that works...

Put the flood table below the barrels (barrels with media) and above the sump. It'll get clean water that way.

Good luck! Do post some pictures, we love pictures.

Rick

Hi Markcaso,

Everyone will tell you to slow the water flow down. I believe in getting maximum flow from the pump through the GB for maximum filtration. The way I achieve this is by introducing an air leak into the top of the bell,can be a small pin hole or what I do is drill a hole and fit a small tap (air pump small 4mm type is perfect) Attach piece of the plastic air tubing to the end and use other end in your ear (no not rear) to listen. When syphon is getting to end of cycle slowly crack the valve until you hear it hissing pretty well. If you find that the syphon wont start close the valve abit untill you get a balance between the two (you have a fair bit of leeway). Let the syphon cycle a few times to settle down and should be right then.

It sounds like your second design is the Affnan bell siphon (see picture), if this is so and you need to put weight on the top of the bell to get it to start then it means you must have some sort of water/air lock in the drain below the siphon. You do not need the air lock for the Affnan siphon only the traditional bell siphon.

Remove the air lock and persist with the Affnan as it is by far the easiest and most reliable siphon design.

I agree Simo Affnan setup is great, But the problem is stopping the syphon (as well as the syphon popping up) and rather than slow the flow right down, keep the flow up and extra filtration

I like Chainsaw's tap trick, very neat, adjustable and a lot smaller than the breather tube.

Afnans siphons work quite well but I don't like restricting the standpipe in any way as it tends to increase the drain time.

1 inch standpipes with 50mil bells seem to work well. I think this ratio (1:2) has been mentioned a few times.

The height of the crenalations at the bottom of the bell need to be large enough to not restrict water flow. Holes that are close to equal the pipes capacity seems to work well.

I find the height of the bell chamber above the top of the stand pipe is not critical however more height seems to be better as it allows a vortex to form in the initial stage of syphon creation.

Finally having your drain pipes rising up slightly so they fill with water will initiate the syphon very well over a wide range of flows, i.e. create the syphon in the drain pipe itself and leave the standpipe unrestricted; unlike Afnan's syphon that works due to the restriction of the standpipe. This gives very short drain times and syphons may even break without the need of a breather at all (two of mine will, one will not).

I think his siphon is not stopping because of the airlock, with an Affnan you need the drain to fully empty of water and be replaced with air to get it to stop. The reason it is popping up is also due to the airlock, as the water level goes up out side the bell (with an airlock) the pressure inside increases causing it to float, no airlock = no pressure = no floating bell.

The Affnan will start and stop at any fill rate that is less than the drain rate.

Hi fishfodder,

Thanks for the comments, further to that I have the answer for the crenellations at the bottom, I dont have any

I have devised a different way of constructing my bell (think outside the square) using 90mm and 65mm bell tube, can use what ever standpipe size (I have 32mm and 50mm on 2 of mine). The bell tube (once you have worked out what length) is glued to the screwon cap, no cutouts or crenellations need to be cut in the bottom because the bell tube is supported from the top and is just suspended at the hight you want syphon to cutout, no need for the 10mm break tube either. This also has the benefit that you dont have to have a brick on top, to stop the BS blowing up by air pressure. The distance between top of standpipe and top of bell does not really matter (within reason). Put an air vent hole on the outer edge of the screwon cap.

Although my photos are of my external syphon, same principle applies for an inbed one.

My system has an air lock as well, I over came it with a home made one way valve made from a ping pong ball and a 25mm PVC end cap glued to the bell and a small hole drilled through the top

Thanks for all the idea, I will give them a try and I will post pictures as that may shed some light on this and may expose any problems I might be overlooking. Thanks

Here are some pictures

More pictures

I'm still having problems with the siphon breaking at the end, I've move the tubing higher than the bottom of the bell housing, but seems to continue, sometimes it breaks. Question? some have mentioned the problem is below? Does that mean under the barrel where the drain is? The standpipe connects to a 90 degree elbow and continues for about 10" to a T before draining to the sump. I notice that the 10" pipe from the T to the Elbow is angled down below the level of the drain pipe, doesn't seem to impede the water flow but could it cause the problem with the Siphon not breaking?

here is a link to a thread with lots of diagrams, some help to explain some of the different situations with siphons very well.http://backyardaquaponics.com/forum/viewtopic.php?f=11&t=5311

In general, if the siphons are starting just fine but not cutting out, the inflow rate to the bed is too fast for the siphon.

However, looking at the picture of your bell, it looks like you just have some small holes around the bottom of the bell instead of big cut outs. I would guess that is the problem. Also under the bed if you can have the drain pipe free drain into a larger pipe so there is an air gap, that can make it easier for the siphon to cut out.

Good Luck sorting it out. I've never really had good luck getting siphons balanced with barrels cut the long way like that. It seems to get the inflow fast enough to start the siphon when the water level is near the top and there for more volume needed per increment of rise puts the flow too fast for the siphon to shut off properly when the water level is near the bottom and it doesn't take much water flow to keep the water level above the air gulp height of the siphon. All my long cut barrels are now on timed pumping.