Backyard Aquaponics
A place to discuss aquaponics

This really is a handy thread. With the bell syphon, is it nessesary for the U airlock or would it work fine without it?

Oh, and does the air tube syphon breaks diameter increase as the bell syphon's pipes increase?

You need the u- bend...or pump water in that fast that it will cover the pipe to kick the siphon off....only problem there is the inflow maybe larger than the outflow

Water will just flow out the drain pipe as fast as it enters without the u-bend.

No reason to increase the air tube size as the pipe size increases

I don't have U bends in any of my siphons - just L bends.

I will second this. In fact, I accidently had a U bend on one and found that it didn't break properly. Here is my take on it:

In the N picture, you can see water gets caught in the "U" part, which means that no air can flow up from the bottom to help break the siphon. However, with the "L" picture, you can see air can freely come up and help.

See I figured it was just reaching equilibrium with the N configuration. The pressure inside the pipe was definately lower than the pressure outside the pipe since I would take the top off and it would all fall back. However, because there is no way for air to get into the system, the tube just keeps siphoning and it never actually breaks.

I actually woke up at about 1am when I realised why 1 out 3 of my autosiphons wasn't working. Nudged it so it wasn't collecting water and it's been working flawlessly ever since.

Make sense?

This is awsome! I never knew about an auto siphon. I use stand pipes with weep holes. This will solve 2 of my problems. Algae stopping up weep holes and a 1 hour drain down time.

Thank you for sharing this!

Gemmell, 2 questions:
1)are you running the pump 24/7
1a)what size pump
2) what size pipe are u using

1)
My pump is pumping water back from the sump to the tank (PIST!), so you're probably not really interested in that.

Water is siphoned from my tank to the beds through 19mm poly pipe with a tap to slow the flow a bit. Each bed (a half barrel) has it's own 19mm poly pipe. It's filling 24/7.

2)
20mm inner tube
40mm outer tube
6mm air tube

Hi Gemmell,

I think the U bend/L bend issue depends on the incoming flow rate to the grow bed.

I have a trickle fill (20 minutes) and aggressive drain (6 minutes) on my second system (pictures will appear soon). I started with an L bend at the bottom, but with such a slow fill rate, the drain part of the siphon would never fill properly to create the airlock required to completely drain. I replaced the L bend with a LKB style cut off U bend and no problems. Because I drain so quickly, when the bed is empty, it easily breaks the airlock and stops the siphon, even with continuous fill.

Just my experience.

gg

I agree 100%. Sometimes just giving it a slight incline will do the job, if your inflow isn't quite up to being able to kick the siphon in with just an L.

Agree with you both - that was why I needed Gemmell's system info

Fantastic thread. Thanks Elk. Will give me some more things to think about and consider. I had been wondering how the auto siphons worked so am very grateful for all this info and will now have to go and have a play in order to sort it all out in my head. Will be great for my home schooling.

I spent over two hours today trying to get a bell siphon to work properly.

The bell portion is of 1 1/2'' the drain pipe 3/4''. System comprised of a 30 gallon tank and a 1/3- 55gallon drum so 17 gallon approx. The pump is a small fountain pump from 130 to 170 gallon per hour max head of 3.5ft. The head I am pumping to is about 2ft. I tried adjusting the flow up and down, tried with a u bend and without also. It would siphon OK but not shut off. Could hear the sucker sucking air but then she would start trickling the same amount as the pumps flow. Could not for the life of me figure it out.

So I took a look at the other bell siphon I made out of 2'' and 1'' pipe which worked a charm and compared the two. The difference was the air line in the new smaller version was of a smaller ID. The OD was the same as the air line on the larger bell I had constructed. Put a larger ID one in her and she liked it and decided to do what I needed her to.

The growbed fills in 4 minutes and drains in 2. Yea 10 pump cycles an hour might be a bit much, but it is better than no biofilter at all which is what these poor convicts have been putting up with for several days.

I'm beginning to think 2:1 is some kind of magic fill/drain ratio. I haven't heard of a siphon that was very far from it.

My D&F seem to be working find but I’m wonder if these time sound correct.

Tank 580gal
GB 260 gal

Drain starts up ~2min before the air bubble is pushed out and 5mins of full drain speed. It takes about 1min more for it to stop. It fills in 8mins for a total of 16mins per cycle.

My main question is the siphon starts before the water gets over the U bend and it seem the pump has a hard time getting enough water into the grow bed to push the bubble out of the U bend. I’m thinking that if the pump slow down the siphon will not start fully. Has anyone ever had this problem of the siphon starting but not ever really getting going resulting it the grow bed remaining flooded?

Thanks
Bruce

I think this is a pretty common problem, you have to get the inflow right in order to get the thing to start. Alternatively you could reduce the size of your siphon (which should make it easier to start).