Backyard Aquaponics
A place to discuss aquaponics

Hey all,

I'm a new member to the site, although I have been lurking here for quite some time absorbing as much of the useful information that I can to build my first aquaponics system. I've run into a roadblock with my loop siphon which I can't get to drain the beds properly.

My system is 2 half barrels filled with a mix of scoria, river pebbles and expanded clay. Each barrel drains out through its own bulkhead and has a guard, the outflow pipes meet underneath the barrels with a T connector, the bottom leads to the long outflow pipe, which is also the loop siphon. The inflow pipe from the pond The top of the loop is fixed about 3/5 from the top of the barrel, and media is filled to about 4/5. The pipe leads to the pond where it sits just above the waterline and falls into the pond to add a little extra aeration. The pond holds between 1500-2000 litres of water, and currently doesn't have any fish in it (though I have ducks so nutrients is not an issue). I tested the loop before I fastened it and it seemed to work (at least it flooded, then drained once when I moved the top of the loop lower), but now I can't seem to repeat it - it simply fills up the left barrel and its awful lot of water to waste for just trial and error - so hoping someone here can help. I'm using 19mm flexi pipe and my pump has a maximum flow for 6000 litres per hour. There is also a splitter on the pond pump diverting water to water feature on the other side of the pond - though it doesn't seem to affect inflow rates much at all. I've attached photos below to help diagnose the problem.

When I turn pump on, the left barrel fills up faster than the right, though they are close to level, but before they level the left barrel overflows - both barrel water levels are higher than the top of the loop when this happens. The siphon never kicks off and no drain happens.


Thanks in advance for any advice you all may be able to provide

*bump* help, please?

Sorry, I think you slipped through the cracks.

I think you've got overkill on your pump, and it could be causing the issues, more water is pushing through than the size of the siphon can handle.

I've got a 8000Lph pump, that goes for more head height, and more distance than yours (so flow at the end will be less), and it happily kicks off 4 x 40mm standpipe bell siphons.

Can you change to a regular bell siphon?

Or double check rocks haven't gotten sucked up and are blocking it up.

Normally you would have a loop on each GB and that is not a loop (it should be round), multiples on a single loop do not work properly (well in my experience).
EB used them quite a few years ago but it was a loop for each bed, there is a pic somewhere showing this setup.

And as Colum said you have to tune your input to the capacity of the loops to dump water.

Thanks for the replies, seems I have a few things to check - I will see if I can reduce the water pressure coming in, perhaps I'll lead the pipe higher before bringing it down to the barrel (which should send a greater volume to the water feature, and less into the barrel). I will definitely double check the rocks. I will also make the loop much loopier.

I was hoping to avoid building or constructing a bell siphon as I thought this might of been the cheaper/easier option - I will switch if it comes down to it I guess. I am curious though why multiples on a single loop don't seem to work as well, have you guys any theories whilst I scurry away to check these fixes? Also how can I search up this EB character and his setup (I searched members, but no EB found)?

I would try making a loop siphon for each bed.

maybe you may have too much flow for the single siphon.

The problem with a loop on multiple beds is mainly that if one bed empties before another it breaks the syphon. I stopped this happening with ping pong balls in the standpipe but its much easier and more reliable to have each bed with its own loop.

As I said EB's system had a fairly large number of half blue barrels on loops I just can't find a decent pic of it.

Alright, so I've taken the advice on board and made some fixes but we still aren't quite there yet;
- I reduced the inflow from a 19mm pipe to a 13mm pipe, then split the 13mm inflow further to enter both tanks at same time
- I added an extra loop so that there is one for each barrel now, which connect to outflow through a T connector
- Cleaned out and secured media filter

I've attached photos for reference


Problem: Left barrel was overflowing and the siphon was not starting = fixed

New problem: Flood and drain is happening very erratically. The first cycle seems fill more or less equally, then after about 75% height (by that i mean 25% below top of loop) one or both begin to drain. After this, it just kind of loops random, it fills and drains unpredictably, neither barrel ever quite reaching the water level at the top of the loop. Likewise it will often spend much time filling and draining at the same time, so the water level rises/sinks very very slowly - until it doesn't want to anymore, and then it doesn't. It has only overflowed twice during early tests, and both times just nudging the piping at the outflow T seemed to kick the drain off.

Sleepe, is this the type of issue you were talking about with one bed emptying before another? Any other reasons that it may not want to behave in a consistent manner? Is it supposed to be relatively consistent?

I know it was said earlier, the beauty of the standpipe/bell siphon, is that it can't overflow easily, unless the pipe itself is blocked. It may not work properly unless properly tweaked, but it'll still drain, and won't overflow.

And with the problems, you could be getting water locked. So the air isn't making it back up the pipe after the first drain.

No that would not normally happen with two loops. However I noticed you have taken the pipe after the t junction over the support of the GB (on the left) you have effectively created a lower syphon.
And it would have been better to have just ommitted the tee and just ran the pipes into a larger pipe eg pvc slightly inclined towards the pond.

Possibly your next improvement should be an RFF between the pond and the GB's, ponds have a habit of filling GB's with crap very quickly as this happened to me early on.

There is nothing beautiful about bell syphons Column.

Beauty is in the eye of the beholder.

They were inspired by and created in hell just to make our lives more miserable.

I don't know what you're doing with your siphons :p

Perhaps I should correct myself; that should have been "your lives".

I remember when they were the up and coming thing on the forum (bit like hula hoops) I thought it was just a silly fad that would vanish in time. Take a perfectly good standpipe that you could shove your hand down or just inspect then fill it with a device that 9 out of 10 people don't understand who it works, classic.

Tried the bell siphon when I first built my system. Didn't like them at all. Went to simple, easy to use/adjust loop siphons.

As to Aku's system, disconnect your drains, make each drain line a separate drain to wherever your draining to, and install valves on each inflow line so you can get a better control over your inflow to be less than the outflow. Any excess pressure you may be restricting from your pump shouldn't hurt the pump. If you want to relieve the excess pressure, install a line with a control valve (before your inflow valves) going back into your fish tank. A little larger diameter drain line wouldn't hurt, either. It may take a bit of trial 'n error, but you must balance your inflow less than your outflow. Valves will allow you to adjust your fill time. All you need is water coming in just fast enough to make the siphon work.