Backyard Aquaponics
A place to discuss aquaponics

I'm having trouble getting my bell siphon to work. I haven't been able to get it to actually initiate the siphoning action. The pipes fill up with water but water stops draining as soon as it gets even with the stand pipe. My stand pipe is 1 1/4" and the siphon pipe is 2". There in no angle or extra plumbing at the end of the drain pipe, it just extends beyond the grommet a bit and ends. Why won't my grow bed drain/siphon? I have plenty of pics for ya'll if I can figure out how to post 'em. Any help is greatly appreciated

To post pics, first make sure to re-size them to 800 x 600 so they will fit the screen for most people and we don't have to scroll sideways to read the posts. jpg is generally a good format to use here.

In the post a reply (not quick reply) scroll down below the preview submit save and cancel buttons and upload the picture as an attachment. FYI the pictures will automatically show up in reverse order of how you upload them and you are restricted to 3 attachments in a single post though you can post as many times in a row as you like.

Ok, how I'm reading this is the bed gets to the "flood level" and just trickles over the stand pipe in the siphon and stays at that level trickling over. This is usually a sign of the inflow to the bed not being fast enough for the size of siphon you have.

One trick that might let you get buy with the size siphon you have and your current inflow if it is not wayyyy too slow would be to add a couple elbows at the bottom of the drain. How this helps is to trap a bit of air in the stand pipe and force the bed to flood a bit deeper in order to force the bubble down through the trapped water in the elbows and allow your siphon to kick in even with the slow inflow rate.

Have you tried tinkering with a couple elbows on the bottom end yet?

If you haven't already checked through it, here is a thread that might be able to help you figure out what's going on.
http://backyardaquaponics.com/forum/viewtopic.php?f=8&t=685&st=0&sk=t&sd=a

There we go, half the problem fixed.
Now to get her siphoning. I'm thinking it has to do with the top of the stand pipe in relation to the top of the siphon pipe? Maybe I need to cut slits in the top of the stand pipe or bring the cap closer to the top of the stand pipe? My other guess is the lack of a water trap at the very end of the drain? Obviously I'm not very good with fluid dynamics. Thanks for helping me with pics.

there is a minimum distance between top of standpipe and cap of bell, there is no maximum I have yet come across.
I would suggest adding the trap at the bottom of your standpipe as TC suggested.
Altering the height of your standpipe will imho provide little assistance in this issue.

looks like your stand pipe is 40mm or bigger, this is quite big for a bathtub usually, unless you're pumping in real quick.

Add the trap and see how it goes

We have suction! The water trap worked like a charm. Thanks guys, I may be able to try my hand at this aquaponics thing after all.

90% of bell siphon problems can be fixed with a larger/taller siphon pipe. 9% can be fixed with a cheater airbreak tube, cheater bottom bends, or larger crenelations. The other 1% probably used too wide of a siphon pipe, have extra holes where they don't belong, forgot the siphon pipe cap, need to shorten the airbreak tube, or have too many bottom bends.

No trying your hand about it. As soon as you built the bell siphon, you were hooked You had to try and try till ya figured it out.

Ok, watching for your system plans in Member Systems now (and of course the next system and the bigger system )

yeah, it's that last one that catches you out though, cos it seems to make no sense at all!

I'm a very visual kind of person, once I saw it in action it made perfect sense. I've been learning a ton lurking around these forums, it's incredible how much info there is here. I'm in the process of setting up my greenhouse and it's on from there. While I've got everyone's ear I'd like to pick your brains on a few questions I have:

1. What is everyone's opinion on lava rock for the gb media. All I could find were a few people that said it may be slightly high in heavy metals and perhaps iron, while others said it should be just fine. Any first hand experience? I'll probably end up mixing 50/50 with expanded clay.

2. It looks like the common grow bed to fish tank ratio is at least 2:1. Do you measure the volume of the grow beds while they're filled with media or empty?

3. Any links or explanation of the ammonia and nitrate/nitrite (?) cycles would be awesome.

4. Is there any gb media that helps buffer down (more acidic)? I've heard very old wood works well but dirty's up the water and could possibly effect the fish long-term. Any suggestions or safe types of wood?

1- yes lots of people use lava rock. Our friends down under often call it scoria and many of them use it. Drawbacks are that it can be rough on the hands for planting in but it does provide trace nutrients and lots of surface area for bio-filter. I've used larger lava rock around the drains in my system to help keep the smaller rocks back and improve the flow to the siphons. Do make sure to rinse lava rock well before putting it into a system as it usually has lots of dust in it. I've used river pebbles with the lava rock through if you have the budget for the expanded clay I hear it is really nice to use.

2-When figuring that grow bed to fish tank ratio, just use the total volume of the grow bed container compared to the fish tank container. Actually the most common ratio is probably 1:1 but if you want to grow as much fish as possible in your amount of fish tank then you go to 2:1 and have to add a sump.

3-The Useful Information section of the forum is an important section to read through
http://backyardaquaponics.com/forum/viewforum.php?f=11
And here is the direct link to what Steve wrote about the nitrogen cycle.
http://backyardaquaponics.com/forum/viewtopic.php?f=11&t=131

4-My general answer about buffering down is don't bother. If you have limestone media, you won't be able to keep it down because the media just buffers it right back up again. If you are just worried because your well water has a pH of 8 or something (my well water does), then rest assured that the nitrogen cycle will generally bring the system pH down as you cycle the system (mine dropped below 7 and kept going down) and you will likely wind up needing to add something to buffer the system to keep the pH up (I added a grow bed full of washed shells). I've tried to see if using wood chips in a system would counteract the pH of the washed shells in a system before and it doesn't. My system pH is pretty solid in the mid 7 range. 7.4-7.6 This seems to be ok. If you really must try some media that could have some downward pH effect (though I doubt it is worth the trouble) I would suggest testing out some coco coir, it will turn your water dark too though.

1
I use scoria. I washed my first batch and had no problems.
I didn't wash my second, as there are many trace elements in the dust.
The second batch due to 0 washing caused very murky water for approx 1 week, and also a buffering of the pH.
These things combined caused me to lose some fish.
Using scoria, I would advise a potting trowel and rake. Using your hands is possible, yet when you're finished it looks like you chewed your nails down to the quick, and they're a touch tender.
So I'm going to keep my dust, and add it in smaller quantities to the system. See what effect that has.

2
ultimate ratio is 2:1 minimum is 1:1 but it's really just a guide. You can match your stocking density to match your GB volume. Or if you have heaps of GB and very small FT, you match your density to your FT.

3
What TC said.
There's also a wiki entry: http://en.wikipedia.org/wiki/Nitrogen_cycle

4
As TC said, if you have a buffer, you'll never overcome it. If you have a neutral system, the nitrogen cycle will bring it to 6.5 - 7 or sometimes crash it completely. Until coming to AP, and finding ppl with limestone gravel buffering their pH up, I'd never heard of a reason to want to bring pH down, it was always a struggle to keep it up.

How do you guys keep the bell siphon from floating? Mine keeps floating off the stand pipe and preventing the siphon from starting.....

LB,
Show us a picture of your floating bell to give us a clue as to what is happening.
Current thoughts are
1 that you dont use an air bleed tube to the top of the bell
2 that the siphon tube has too much 'back pressure' , or even an air lock, to prevent the air inside the bell from venting
3 that the Flood rate is very fast? causing the bell to float before water exits the siphon pipe
Just thoughts at the moment until we see what is actually happening.

Cheers IanK