Backyard Aquaponics
A place to discuss aquaponics

Some of my bell syphons aren't working. They kick when the GB is full, but fail to shut down, even when I slow the water to a trickle.

They are 25mm standpipes, with 55mm 'bell part'. I am growing in half barrels. I tried searching but couldn't find an appropriate thread.

What are some of the things I can do to troubleshoot? I see some bell syphons have small tubes running from the top, would this be helpful?

Thanks in advance.

Plachon there are a few things that can go wrong with running multiple siphons and when you say some are working and some are not, that would indicate to me that there is not enough flow over the whole system.

I think you will find that if you shut down the siphons that are working the others would start to work, you don't say how many siphons you have but try shutting down the working siphons and see what happens.

Your siphon operating issues aside... Your standpipes are overkill for half barrel GB's and would be requiring a lot of water flow, giving very fast F&D cycles, which won't be allowing the fines to settle out in your GB's... 15mm standpipes would be more than sufficient, I use them for up to 200L GB's.

As far as your siphon issues are concerned, with bell siphons the K.I.S.S. principle is the best method. Breather tubes and inverted reducers atop the standpipe etc, are not required. See the pic below, these siphon kits are extremely reliable, but they are very basic, with no attachments or widgets.

If you follow the these guidelines you should have a reliable siphon:

- Bell a minimum of 2x the diameter of the standpipe, I prefer 3x.
- Sufficient slots/holes near the base of the bell (but not at the very bottom) to allow free water flow.
- Sufficient slots/holes in the outer gravel guard.
- Use as few fittings as possible in the standpipe and try and make the flow through the standpipe as smooth as possible.
- Have a vertical drop of a few inches below the GB, then a 90º elbow, then about 200mm of horizontal pipe for 25mm, or about 100mm for 15mm.

Then it all comes down to tuning the water flow into the GB.

Im amazed that new posts pop up about syphons issues???????????????????

Let the search function be your friend.

Yup!...

Thanks for your help. I did try the search function before posting. If the standpipes are too large, then can I use a reducer or will I have change the whole thing, including elbows?



The KISS principle seems best, but in my case adding a breather tube and slowing F&D cycles may do the trick?

Plachon... I put a 25 to 20 mm fitting on a syphon outlet a while back... seemed to help it start with less water. But I'm not sure if it impacts on the size of the window between the siphon not making and not breaking. Others might know.

As for the breather tube/snorkel, I think most of the experienced people on this forum say it's not needed. (seems more commonly used in US for some reason). I've read hundreds of bell syphon posts and been very close to installing a snorkel in desperation - hoping to get more flow through my growbeds. Have tried all sorts of other solutions but nothing helped much.

BUT... today I made a new bell - modeled on Mr Damage's picture above. With slots are a few cm above the bottom of the bell and horizontal. Previously had slots cut out of the very bottom of the bell.

Until today, at the desired flow level, the syphon would struggle to break for minutes at a time during the first few cycles then not break at all. Now it's breaking immediately and every time. Wish I'd taken more notice of your design long ago Mr Damage... you're a champion!

Cheers Dave!... It's a pleasure being able to help people get their systems on track and make their AP journey a little more enjoyable...

As I've said dozens of times before on here and elsewhere, when it comes to siphon design... the K.I.S.S. principle reigns supreme!

so how did you make the slots, angle grinder?/ hand saw?/

Drop saw, but people have done them with a hand saws and angle grinders. it's difficult to hold the pieces safely when using a grinder, even if you leave the pipe full length while cutting the slots, so just remember to do a finger count when you've finished... or use a vice etc... much safer and will make for a neater cut.

I've used angle grinder for similar slots in pvc pressure pipe in the past (not a bell syphon) - but agree that I was lucky to come out of it with all my fingers.

It was easy with a small hand saw and a rotary tool kit (cheap version of a Dremel) for the vertical cuts at each end. If I didn't have the rotary tool, I would have done it with a drill.

or, if no powertools... maybe use string as at https://www.youtube.com/watch?v=Dp8PSWHpSD8 - I've never tried it out. Seems a bit unlikely but seeing is probably believing.