Bell Siphon problems in paradise

[N.G.]

Hello all. If there is anyone that can help me please I would greatly appreciate it. My bell siphon will initiate a steady, good flow within 30 seconds, but stops leaving about 5 inches of water in the grow bed each time. I am stumped as to why that is. My stand pipe is 3/4", my bell siphon is 2" wide lined with 1/2" holes along the bottom. The downspout has a right angle about 6" vertical, 7" inches horizontal and an elbow at the end to control the back pressure. I've tried playing around with that, but it doesn't change anything. I would be more than grateful if anybody has suggestions. Thank you!!

[Jonathan Kadish NYC AA Chair]

Well this might or might not fix this problem but you want a reducing elbow at the bottom of the standpipe going from 3/4 inch to 1 1/2 inch and having the pipe leading back to the fish tank be 1 1/2 inch pvc. This allows free flow from the stand pipe and allows air to enter from the bottom to break the siphon when the flow slows when the bed is nearly empty.... I hope that is the issue :)

[Jim Joy]

From your first picture, it looks like the bell is longer than the stand pipe.  There has to be room for the water to overflow the stand pipe, but not too much.  The siphon works because of low pressure that forms under the bell cap.   Try trimming the bell length to about an inch higher than the stand pipe.  The water depth when the siphon breaks should be the depth were air enters the bell at the bottom.  My best guess from the pictures and your description is there is too much head room in the bell which is allowing only a weak siphon to start.  

That said, five inches of water left in a 12 inch deep grow bed is not a bad idea.   In my climate of the low Sonoran desert, water left at the end of the cycle stabilizes the bed temperature and provides moisture if the siphon fails to break - holding the bed at a low water condition.  

If the flow starts, your stand pipe to sump or fish tank is working properly.   

[N.G.]

Huh. a reducing 3/4 inch to 1 1/2 inch elbow? Never heard of that. Is that a common piece I could find at the hardware store? I just picked up a stronger pump, to see if that might be my problem. maybe that will help? I will definately search for that piece. Thank you so very much!

Jonathan Kadish NYC AA Chair said:

Well this might or might not fix this problem but you want a reducing elbow at the bottom of the standpipe going from 3/4 inch to 1 1/2 inch and having the pipe leading back to the fish tank be 1 1/2 inch pvc. This allows free flow from the stand pipe and allows air to enter from the bottom to break the siphon when the flow slows when the bed is nearly empty.... I hope that is the issue :)

[N.G.]

Jim Joy said:

From your first picture, it looks like the bell is longer than the stand pipe.  There has to be room for the water to overflow the stand pipe, but not too much.  The siphon works because of low pressure that forms under the bell cap.   Try trimming the bell length to about an inch higher than the stand pipe.  The water depth when the siphon breaks should be the depth were air enters the bell at the bottom.  My best guess from the pictures and your description is there is too much head room in the bell which is allowing only a weak siphon to start.  

That said, five inches of water left in a 12 inch deep grow bed is not a bad idea.   In my climate of the low Sonoran desert, water left at the end of the cycle stabilizes the bed temperature and provides moisture if the siphon fails to break - holding the bed at a low water condition.  

If the flow starts, your stand pipe to sump or fish tank is working properly.   

Hi Jim, the stand pipe is 1" shorter than the bell siphon. I believe I read it should be between 1-2" shorter but in guesstimating the height of my grow bed because it is cylindrical the water was coming up higher than I wanted so I was planning to trim it down anyway. I just want to make sure, Are you suggesting that I have more than an inch in between the stand pipe and the bell siphon? I guess the 5 inches of water wouldn't be bad in the summer when it's in the 90s, but I'm just confused as to why that is... and then when it gets cooler as it gets into the 20s I imagine I'll want it to work as it should??? Thank you so much for your suggestions! Big hugs to everyone :)

[Jack Dunbar]

Hi N.G.

I was always told that your bell syphon should only be twice the size of your stand pipe . You said your stand pipe was 3/4" so your bell should be 1 1/2". What I did on my (2)40 gal Growbeds was use a 1/2" standpipe w/ 1" bell syphon and I also used a 3/16 " hose attached to the 1" cap at the top of my bell syphon that goes down the side of the bell syphon and ends at approx3/8" above my holes on the bottom of my bell syphon. I also put a small pill bottle on the end of my 3/16" syphon hose. The bottom of the bottle lines up with the bottom of my 1" bell syphon. My syphon starts and stops great and the only issues that I've had is when I have a plant with a good root system that gets into my syphon. I also took a 4" pvc and made horizontal cuts around it and I silicone it to the bottom of my growbeds. I made sure that I went big enough so if I needed to pull my syphon out that I could get my hand in there to clean out any roots or whatever. My system has been up and running since last Nov 2013 w/ no issues. You don't need a lot of room between your stand pipe and you bell syphon as mine is proof of that. I hope this helps you. Take care

                                                                                                 Jack 

[N.G.]

Hmm. Yeah, the fact that my stand pipe is 3/4" and my bell is 2" did cross my mind while I was at the hardware store, but that is all they had. There is a plumbers store close by I'm sure I could pick up a 1 1/2" pvc there. I will give that a try tomorrow. I tried the new and stronger water pump and it stopped at about the same point. It just gradually lost it's steam and trickled to the point of stopping, no gurgle. I did notice though as I was watching it, since the test cap on the bell is somewhat transparent, the water was string at first siphoning so powerful the water was hitting the cap and then it gradually slowed and wasn't hitting the cap after a while. It took about 5 minutes for it to drain from an 11.5" height to 5.5".

 I have seen those breather tubes. Is that similar to what you have on yours? I don't know much about that as I was trying to start simple but hey I will try anything, well almost anything. I'm not to keen on revamping the whole system since it did take some time to silicone and paint the grow bed and such. Will that tube help it to drain all the way? Thank you for your time and effort!

Jack Dunbar said:

Hi N.G.

I was always told that your bell syphon should only be twice the size of your stand pipe . You said your stand pipe was 3/4" so your bell should be 1 1/2". What I did on my (2)40 gal Growbeds was use a 1/2" standpipe w/ 1" bell syphon and I also used a 3/16 " hose attached to the 1" cap at the top of my bell syphon that goes down the side of the bell syphon and ends at approx3/8" above my holes on the bottom of my bell syphon. I also put a small pill bottle on the end of my 3/16" syphon hose. The bottom of the bottle lines up with the bottom of my 1" bell syphon. My syphon starts and stops great and the only issues that I've had is when I have a plant with a good root system that gets into my syphon. I also took a 4" pvc and made horizontal cuts around it and I silicone it to the bottom of my growbeds. I made sure that I went big enough so if I needed to pull my syphon out that I could get my hand in there to clean out any roots or whatever. My system has been up and running since last Nov 2013 w/ no issues. You don't need a lot of room between your stand pipe and you bell syphon as mine is proof of that. I hope this helps you. Take care

                                                                                                 Jack 

[N.G.]

                 Wait, I did add the 1" inch funnel to the 3/4" to help initiate the flow. Wouldn't that make my widths okay? Since my stand pipe is 1" and my bell is 2"???

[N.G.]

Sigh. I am so stumped.

[Alex Veidel]

It leaves 5 inches of water? Maybe you have a air leak in your siphon bell.....I'd double check and make sure everything is fitted tightly.

[Alex Veidel]

And Jim is right, you should only have a couple inches from the top of your stand pipe to the the inside ceiling of your bell.

[Jim Joy]

The breathing tube,  AKA snorkel, is to help stop the siphon by introducing air a second way to break the vacuum under the bell cap.  If you have a lot of water entering the media bed or have a long horizontal run of pipe, the snorkel may be necessary.  The snorkel length determines the water depth when the siphon will stop.  There are a lot of YouTube videos about how snorkels work.

[Jim Joy]

Hi Jim, the stand pipe is 1" shorter than the bell siphon. I believe I read it should be between 1-2" shorter but in guesstimating the height of my grow bed because it is cylindrical the water was coming up higher than I wanted so I was planning to trim it down anyway. 

1 to 2 inches between the top of the stand pipe and bell pipe cap should be fine.  Is there possibly an air leak between the bell pipe and cap?  Sounds like you are losing the vacuum under the bell before the water reaches the bell pipe holes at the bottom.   My bell siphons are just press fitted together, not glued.  It works for me.