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Bell Syphon Problem
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Author:  tomnick [ Mar 30th, '19, 02:27 ]
Post subject:  Bell Syphon Problem
Hi everybody,

I built my first IBC aquaponic system and I am having problems with my Bell Syphon. Since I live in Germany and we do not have the Australian pipes I am using HT pipes. The problem I have is, that at a certain level the water runs but does not produce any vacuum by itself. As son as I lift a bit the bell pipe, it creates vacuum and runs like a charme. Any idea what could be wrong ?

Configuration:

Stand pipe 40mm Length in the IBC 190 mm
Bell Pipe 75 mm Length in the IBC 200 mm

Pictures enclosed

Thanks for some help and have a nice weekend
Tom

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Author:  arbe [ Mar 30th, '19, 07:22 ]
Post subject:  Re: Bell Syphon Problem
Do you have a tap/valve controlling the water flowing into your growbed? Usually when a siphon won't stop the flow is too great and when it won't start it is too low - you need to find the sweet spot.

If you do a search on this forum you should find lots of information about siphons.
Author:  tomnick [ Mar 30th, '19, 11:00 ]
Post subject:  Re: Bell Syphon Problem
arbe wrote:
Do you have a tap/valve controlling the water flowing into your growbed? Usually when a siphon won't stop the flow is too great and when it won't start it is too low - you need to find the sweet spot.

If you do a search on this forum you should find lots of information about siphons.



Since I am runnning it on a test I am using a regular garden hose which should have enough power
Author:  DanaPT [ Mar 30th, '19, 22:46 ]
Post subject:  Re: Bell Syphon Problem
I have had my system for 3 years. When I first started I got the bell siphon to work fine. As i added plants and roots took hold the flow changed. Siphon didn't work so well. My fix was to drill a small hole in the stand pipe. The timer floods the GB and when the timer runs it course it shuts off. With the hole in the stand pipe the water will drain emptying the GBs.

I'm sure I wasn't the first, but it does do the trick and will get you past this point.
Author:  Santaria [ Mar 31st, '19, 18:36 ]
Post subject:  Re: Bell Syphon Problem
In my limited opinion I don't think the opening to the stand pipe is big enough. Are you able to put a fitting on the top that will take it to the next 2 sizes up? Will let more water in initially to start the siphon.

Sent from my Pixel using Tapatalk
Author:  Mr Damage [ Apr 1st, '19, 13:25 ]
Post subject:  Re: Bell Syphon Problem
tomnick wrote:
The problem I have is, that at a certain level the water runs but does not produce any vacuum by itself. As son as I lift a bit the bell pipe, it creates vacuum and runs like a charme. Any idea what could be wrong ?
Simply not enough water flow to initiate the siphon. A 40mm standpipe is huge and will require a massive amount of flow to get it working. It's also way too large for an IBC type GB.

I make and sell bell siphons in a variety of sizes to suit different sized GB's and have done a fair bit of testing that regard over the years. For an IBC type GB we use a 20mm standpipe and with the inflow tuned properly to get it working it gives around a 15 minute F&D cycle, and that's in a GB with a 300mm gravel depth, if yours is shallower it will be a shorter F&D cycle time.

If you step up just one pipe size to 25mm it requires about twice the pump flow into the GB and gives a F&D cycle time of around 6-8 minutes, and can lead to water turbidity, as everything is flowing and filling and draining too quickly for solids to settle out.

The largest siphon kit we sell is for GB's from 600-1200L capacity and that only utilises a 32mm standpipe.

Slots in the outer gravel guard also help. The expanded clay beads can get sucked into and block the holes.
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