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 I have been trying to get this bell siphon to work for a week now. i have 2 2'x3'x9" drain tables and according to this pdf doc.: I have the measurements right. It works fine without the media in it, but when I add the gravel the siphon will not break. Any ideas? I am at the end of my rope and have seriously considered taking the saws-all to the entire system.

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I am very very new to aquaponics, just started learning about it a couple of months ago.  I am starting to build my first small system... I'm talking, 10 gallon tank and 10 gallon grow bed, and figured I would try building a bell siphon.  I am so grateful for this community and glad to have seen Rob Nash's How To Build A Bell Siphon, which I plan to use as my template. (Thanks for posting Rob!!). 

So, I have some questions as to the size of the bell siphon.  The container I have for my grow bed is (inside dimensions) 19" length x 14" width x 8.5" height.  Since my grow bed is not the normal 12" height, will the diameters of the pipes and snorkel (from Rob's template) be alright to use on my shorter grow bed?  If I just shorten the stand pipe, bell pipe, and snorkel accordingly, will that be the only adjustments I would possibly need to make or would the teeth on the bottom need to be a different size too?  Also, would a 3" media guard be alright to use or should I stick with 4"?

(Also, I just want to note that I do not have a water pump or any plumbing yet as I am still in the process of gathering up all the bits and pieces to put my system together:)


Rob Nash said:

here is a bell siphon how-to by Rob Nash, these cost about $10 to  build. 

i have one that has worked without fail for 2 years now.

Hi Erin,

I used a different set of instructions ( for my Bell siphons, but my grow beds are also about 8" deep and they work just fine. As you said, you'll need to shorten the pieces to fit your bed depth, but it should work just as well. I used a 3" gravel guard and that has been working OK. The only drawback to the smaller guard, I guess, is that it may be harder to clean out later if it gets clogged with roots or plant bits. I've only had mine going for a few months, so I still have that to look forward to. I really like the uni-seal design instead of the bulkhead connector because I find it very easy to adjust the drain height, but it sounds like they both work. Good luck!

 yea i wish i had a uniseal, but i just unscrewed the standpipe (is that the right term?) from the bulkhead to heighten it and tg it is still working. thank u very much Tom. i used the same design as Tom. if u would like measurements i will get them for u and post asap. i used a 3in gravel guard and i can stick my hand in there just fine (no torque though). i wanted the smallest stuff i could use for the bell siphon since it takes up grow space. with that in mind i bet u can go with a 1/2in standpipe and and 1in siphon. check out the link above. let me know how it works.

I thanks for the link!  It's really helpful, and I am going to incorporate those instructions into the construction of my bell siphon.  I think I will go with the 3" gravel guard too.  

I have not been able to find Uniseals locally.  Most stores I have checked with do not know what a Uniseal is anyway.  I show them a picture too, but they've never heard of it.  I have found them online, so I will order some this week.

Another question, do you think it matters if the snorkel tube is clear or black?  Is black a better option to control potential algae growth? 

I haven't had mine long enough for algae to be a concern, but I suppose black would make for less growth when water is in the tube. Not sure it will matter since that tube has air moving through it at the end of each drain cycle, but I don't think it would hurt anything to use black. 

 Erin, I am so sorry my gravel guard is actually 4in. i was mistaken.

 Did u try to ask ace about the uniseal? i intended to do that, but i have not gotten around to it yet. i had the same problem as u when i wenting looking for one... a lot of blank stares, lol.

 Measurements for my gb/siphon: Pump: 210 GPH, pump tube has 1/2in T which slowed it down to 80 GPH; GB (1/2 50 gal. barrel): 2.5 cu ft of media (pea gravel), water fills to 7.5in, media is filled to 9in; Drain spout (starting from tank): 3/4 x 5 in pvc connected to 90 degree elbow connected to 3/4 x 11.5 in pvc connected to 90 degree elbow connected to 3/4in bulkhead connected to 3/4 x 6.5 in standpipe (lengths were measured with connectors attached); Bell siphon: 1.5 x 7 3/4 in pvc, 3 tabs are 1in high, 1/2 x 6 in snorkel (black) attached to cap w/ 90 degree elbow; Gravel Guard (perforated corrugated drain pipe): 4(ID) x 11 in.  

BTW... the siphon is still working!!!!! Hopefully soon I will be taking it for granted. TYVM everyone for your invaluable help and hopefully other people will be helped by this thread also.

Chris, hahah! yeah the blank stares are priceless... They think I am making it up or something (until I whip out my phone and show them what a Uniseal is).  Then they swear their bulkhead fitting is way better than any so-called uniseal!  I went to an Ace store, again the guy didn't know what a uniseal was, he but tried to steer me towards a "really good" copper bulkhead fitting... I was like, dude.. I can't use copper! are you nuts! haha

Anyway,  thanks for sending the siphon info and congrats on getting your siphon to work!!  This thread was very helpful for me as well.

Funny because the parts I got through Amazon were from an Ace Hardware store. I got about the same reaction when I called the local store to get more. The guy was helpful and I thought having the Ace part number from the Amazon parts would do the trick, but he couldn't find the number because they don't stock it.

Congratulations Christopher! It sounds like you persevered through the rough part. I've been following this thread from afar as I've been busy designing a bigger custom system.

So, good for you! Thanks for your posts- this has been a very good thread, I plan to refer to it from time to time as I build more beds this month. I'll post some pix later with our bell siphons -for future readers. Cheers everyone!

 lol, yea lots of blank stares, especially if u try to explain wat u r doing, lmfao (hey, most of the time they ask u that! lol). lol, on the copper. i am very lucky to have a great hydroponics store less than a mile from my house. the owner knows me by name and is very helpful. he still will not carry uniseals though (i had to bring in a pic) and he sold me some bulkheads. i would think that the uniseals would be better since they do not have as many parts to leak as a bulkhead (btw both my bulkheads do leak that is y i am so interested in the uniseal).

 that is weird that ace would not even order it. i used to have them order all kinds of things for me, but i was buying wholesale, that may be y.

 Connie, thanks and thanks for the pics they got me brainstorming. more pics on the thread would be great too. unfortunately i have not been able to do that myself yet, sorry about that, but hopefully i will be able to soon. 


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