Bell Siphon

[Christopher Brickey]

 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.: http://www.ctahr.hawaii.edu/oc/freepubs/pdf/BIO-10.pdf 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.

[Connie Christians]

Jon- Good point about the pump size. I have a larger pump and I have had no problems, other than the fast rate of flow in the very beginning- which was easily adjusted, and I have no snorkel tubing on my auto siphon. It works like a charm, ebb and flow 4 times an hour No need for a timer. I think with regular cleaning every month and rotating old plants out- I won't have issues with clogs either.

[Tom OBrien]

I made my siphons using the same instructions and had similar problems. The document has a pretty good troubleshooting section, but I still had to experiment some with the flow rate. When I first set it up with the media the inflow rate was very slow and I didn't have the added pipe on the bottom, so the water just trickle out the drain without starting the siphon. I boosted the inflow rate quite a bit and added an angle and a short pipe underneath, which worked great for getting the siphon started but made it reluctant to stop. I turned the flow rate back down a bit, and that has improved the siphon stop and also helped increase my fill/drain cycle time which was on the short side.

[Suzanne Carter]

I just want to thank everyone who posted replies to this question as I too am having trouble with setting up my new siphon and feel like giving up! But after reading all the advice I now feel inspired to try a few other options tomorrow to see if I can get it going. So far I can only get it to work if I dump half a pail of extra water in once it is full - otherwise it just trickles over the edge of the funnel and doesn’t create the siphon. Thanks again for being such a helpful resource and community!

[Suzanne Carter]

Does anyone have any suggestions how I could get this bell siphon to work? I attached a video to give an idea what it is doing... if I don't touch it, it will just empty at the same rate it is filling and not activate the siphon. If I lift the bell or add more water from a pail, it will trigger and empty just fine... please help!

[Tom OBrien]

I'm new to this and not an expert, but I found adding pipe to the outlet helped a little in getting the siphon to start. I think it adds a little flow restriction. I'm going to try adding a coupling on mine to reduce the outlet pipe diameter and see what that does. Good luck! 

[Jon Parr]

More inflow is one way. Or reduce outflow pipe size, or try adding a coupler to top of standpipe. The wider diameter of the coupler will create an immediate restriction when the water hits the standpipe, closing off the vent action from the standpipe itself.

[Connie Christians]

The siphon I built is very much like the Hawaiian design using a 1" standpipe- I eliminated the snorkel tubing, made the notches at the bottom of the bell siphon larger. The bed is 12" deep- filled with Hydroton, contains approx. 18 gallons of water. Pump is 400 gph, flow valve is set at 2/3 open and feeds 2 Grow Beds. Siphon shroud is drilled with holes, screened on the inside, cap has 1/4 hole drilled in the top.

It auto-siphons every 15 minutes without fail.

My biggest challenge was Hydroton sneaking in around the shroud and clogging the drain. I sealed the pipe to the bottom of the tank with safe silicon, flushed out the pipes- and that solved it. Hope this helps.

[Heidi Burrows]

Hi Suzanne, Boy do we know what you are going through!  Our bell siphon worked then we went to extend the snorkel as it was a bit on the short side and we haven't been able to get it to work again.  As soon as we touch the top even just a bit the siphon starts... ugh I am sorry I do not have the answers for you but we wanted you to know you are not alone in your quest to find answers!  Good luck!

Suzanne Carter said:

Does anyone have any suggestions how I could get this bell siphon to work? I attached a video to give an idea what it is doing... if I don't touch it, it will just empty at the same rate it is filling and not activate the siphon. If I lift the bell or add more water from a pail, it will trigger and empty just fine... please help!

[Christopher Brickey]

Update:

 So I put a t in the tubing from the pump, to slow down inflow. then i added an elbow to the snorkel. it worked great for several days and then i removed it to test the siphon for the other side (that i do not have full of media yet). it did not work. Then i put the original siphon back in the exact same way and guess what... it did not work either. ughhh! so wat in the world happened? i did not change anything and it stopped working when it was working fine before!

 Then I switched to a T with a bigger 3rd hole and attached a ridiculously large sized snorkel (with elbow, also so ridiculously large that i cracked the cap on the siphon while drilling the hole). That did not work.

 Then, just earlier today, I thought that I would try to make the gaps on the bottom of the siphon larger (from 1/2 in high to 1in high). I hesitated to do that before because I wanted it to empty as much as possible. Now it works just fine. Or at least it has been since this morning. I even removed it and replaced it several times (to make sure it wasn't just a fluke) and it still works just fine. Yeahhhh!

 So here is what I got going... I have a 50 gal. barrel for the fish with 40 gal of water that uses a 23 watt pump (sorry i do not know gph it only says watts on it, i think 300?) that pumps water to 2 gb's filled with pea gravel with an area about 8" x 2' x 3' (the gb's are 1 50 gal barrel cut in half though so it would be difficult to get actual area, since it is rounded). The pump uses a 1/2 in tube that has a 1/2" to 1/2" to 3/4" T. The tube then goes to another T that feeds water to the gb's. The standpipe, bulkhead, and drainpipe are all 3/4". The drainpipe has an elbow coming out the bottom of the bulkhead that goes to a 13" long pvc then another elbow that connects to a 5" long pvc to drain into fish tank. The Bell siphon is 1 1/2" pvc with 3 1in long notches on the bottom and a 1/2in tube snorkel with 1/2in elbow. Of course the snorkel is cut to the top of the notches. I do not know the exact length of the standpipe and siphon, it is something odd because I had to adjust them several times to be right. It drains at about 6 1/2" though, i think. 

 I think that is about it. so after soooo loooong it is seems to be working. I will post more later. Also, something off topic, can anyone tell me how to do the math that I am missing from the explanation ie. area of gb's, gph, how many gal. in gb's, gph to gb's, etc?  

 

[Tom OBrien]

Well, I don't think you can compute the pump flow rate from the pump wattage because it depends on the efficiency of the pump motor and impeller. If you have a timer and a container like a 5 gallon bucket, you can measure the flow rate. If you are getting 300 GPH, it should take (300 GPH / 60 minutes per hour / 5 gallons) = 1 minute to fill the bucket.

The surface area of the gb is just length times width (3 x 2 = 6 sq ft). I guess the approximate volume in feet would be pi x r squared x L = 3.142 x 8"/12" x 8"/12" x 3' = 4.2 cu. ft. There's about 7.5 gallons per cu ft, I think, but obviously when the bed is full of media the volume of water in it will be much less.

Hope that helps.

[Tom OBrien]

Oops. Volume of 1/2 barrel would be about 1/2 x pi x r x r x L. I used r = 8" or 0.6667 ft since that is the height of your media. So that would be 2.1 cu. ft.

[Christopher Brickey]

 Thanks very helpful.

Thomas K OBrien said:

Well, I don't think you can compute the pump flow rate from the pump wattage because it depends on the efficiency of the pump motor and impeller. If you have a timer and a container like a 5 gallon bucket, you can measure the flow rate. If you are getting 300 GPH, it should take (300 GPH / 60 minutes per hour / 5 gallons) = 1 minute to fill the bucket.

The surface area of the gb is just length times width (3 x 2 = 6 sq ft). I guess the approximate volume in feet would be pi x r squared x L = 3.142 x 8"/12" x 8"/12" x 3' = 4.2 cu. ft. There's about 7.5 gallons per cu ft, I think, but obviously when the bed is full of media the volume of water in it will be much less.

Hope that helps.