Bell Siphon questions

[JRComito]

I recently designed and built my siphon, and I wonder how important it is to have a "gravel guard" around it. The other question is how much more effective is a siphon with a snorkel versus without one? I am testing with a tank of water without gravel, so I am aware that the flow rate is going to change. Is it enough to restrict the siphon's flow? Is having the gravel in the bed going to have a big impact on flow, and should I "over-build" the siphon to be ready for that?

Thanks for any help.

[TCLynx]

The breather tube is generally placed so that it is just above the castle cuts on the outside of the bell and it allows the air to get sucked into the top of the bell to stop the siphon.

[JRComito]

That's it! I thought so. Thank you so much for the validation and all of your help. 

[JRComito]

I am glad to report that my siphon is working properly. Many thanks to all who have contributed in some way. Tc, the single 90 at the bottom of the drain coupled with the simplest castle cut on the housing, gave way to the perfect solution for my system's issues. No snorkel. The trap should not be applied in this sized application. I'll post some video soon. Thanks again for the advice.

[TCLynx]

Go as simple as possible at first and only start adding the other stuff if simple doesn't work.

[JRComito]

Well I got it working, but I'm havving trouble getting it to "burp". At least it isn't flooding the bed. It will start trickling down below and stay that way for a long while. I figured out that the inflow was a bit low, so I increased it and it helped. My question now is how much time should pass between end burp and start of siphon at full level or top of standpipe? It drains and stops("burps") in about 2 minutes, and fills in about 9. That seems like it would be to wet. If I up the flow, then I shorten that even more.

[TCLynx]

The rate at which siphons flood and drain beds is going to be closely linked to the size of the siphon, the flow rate and the overall size of the bed.  You are not going to be able to vary the timing all that much since if you change the flow rate too much the siphon either wont start properly or it wont stop properly.

If the inflow is too slow, the siphon will have a tendency to leave the bed flooded while just trickling over the top and not draining the bed.

If the Inflow is too fast, the siphon will tend to drain the bed down and keep it drained down and not stop.

If you add the funnel on top as Affnan does, then you can usually get a siphon to start at slightly slower inflow rates.

Finding the balance between too fast and too slow can be pretty tricky but seeing as I've run beds constant flood.  I don't really see an 11 minute cycle as being too wet.

[Robert Rowe]

Another minor detail which may be a factor in starting the siphon is where the rizer is located in the bed and where your water input is located. I always place the rizer in the center so the water flow is centered and the incoming flow is from above between the bell and the gravel shield again to maximize the flow at the syphon entry.

JRComito said:

Well I got it working, but I'm havving trouble getting it to "burp". At least it isn't flooding the bed. It will start trickling down below and stay that way for a long while. I figured out that the inflow was a bit low, so I increased it and it helped. My question now is how much time should pass between end burp and start of siphon at full level or top of standpipe? It drains and stops("burps") in about 2 minutes, and fills in about 9. That seems like it would be to wet. If I up the flow, then I shorten that even more.

[JRComito]

Thanks TC.

I tried to make a funnel out of a pvc fitting. The bell housing barely fit around it, so I cut the corners off of it and it left a bit more room, but still pretty tight. Maybe 1/8". I'm sure I just need to find the propper fitting. Is the purpose of the funnel to slow things down, and so is that tight fit what I need? For some reason my brain tells me that if you increase the head pressure you force the siphon downward harder. Does that sound right? I am not a hydrologist. :-)

 As for the constant flood, what level in relation to the gravel do you run your constant flood? I am running a constant flow about 1"deep through one of my perlite beds that is about 5" deep. I use it as a propagation tank. The space between the water and the surface of the gravel is where the roots get their oxygen. I guess the question would be what percentage of that space is required for oxygen uptake? I would like to apply this technique to future gravel beds. 

Robert, I have my siphon located dead center just like you say. I agree with your thinking on the flow being centrally focused. Glad to hear I am doing things similarly as others. 

Thanks to both of you so much for all of your advice. I am really starting to enjoy my experience now, rather than being aggravated. I am extremely grateful for this resource. Hopefully, someday I will be able to give back a little. :-)

[Rob Torcellini]

Going back and looking at some of the pictures in this thread...  If you're going to use a trap at the bottom, it's VERY important to have the fittings in it as close together as possible, and to put the trap up as high as possible.  This will aid in the burping effect.  The longer that the bubbles have to travel, the less effective the burping is.  (This doesn't pertain to the affnan siphon, just the bell siphon that I posted the video about earlier)  With my setup, I'm using 3/4" piping for the drain and it's cycling around once an hour.  VERY slow fill rate and it's starting/stopping perfectly.

To slightly contradict about the siphon being in the center:  You may find it best to put the siphon near an edge.  The water flow to it will have nearly no difference and you can then see down into it without having to reaching over your bed to see down into it.  (trust me on this....I know from experience!)

As TC said, keep it as simple as possible....but, also keep in mind that as your system matures and you start getting a lot of roots into your beds, the flood/drain rates will change.  You need to make sure that the siphon will work with varying rates.  Also as pumps get older (worn out/clogged with goo), they can be less efficient so your water flow will slow down.