Backyard Aquaponics
A place to discuss aquaponics

I've got a 25 gallon bed that's got a max water depth of about 4 3/4" (stand pipe length, 3/4" standpipe with male reducer taking up most of the pipe making it more like 1"). I have a 2" bell siphon that's about 6" high. I modeled it off of indoorharvestgardens YouTube example. http://www.youtube.com/watch?v=TpC8O9NqYX0

My bed is on one wide pressure treated plank with the edges of the bed hanging a little lower then the rest, resulting in somewhat of a warped bottom. My bell siphon doesn't rest flat on the floor of the bed and I'm sure this effects it.

My siphon starts in roughly 20-30 seconds but will NOT stop. I attached a tiny air break tube, ran it down to the top crenellation, about 1/8" size tube, and it still wouldn't stop. I built a few siphons but none will stop. Is there a fault in my drain pipe length or siphon length? Nothing seems to be working and im ready to ditch the bell siphon and try something else. Despite my strong interest in a flood and drain bed I might just resort to continuous flow. I've spent two days after work trying to get this siphon to stop on its own and I'm frustrated and discouraged.

Please provide any suggestions, alternate siphons, methods, or just a way to fix this.

My next trial will be going from 1/8 tubing for the air break to 1/2. I'd use 1/4 if I could find it anywhere >.<

The siphons I use are Affnan. Easy, reliable. Most people's problems are caused by their gravel guard not allowing enough water through, and just enough water flowing in to keep the siphon gurgling. All of my gravel guards in the future will be made of that rigid plastic hardware netting that works so well as a fishtank cover. I will just zip tie it into a cylinder the size I need.

I have no gravel in my bed yet, the little that's in there is far from the siphon until I get it to stop on its own. My siphon rests either crooked with the slits being uneven, or it's level with even slits but a pretty decent gap under the siphon. I'll upload pictures later, especially if I can't get it to work. I'm concerned about my non level siphon, if its level the uneven bed floor creates a large gap under one end. I'm almost positive it's not getting enough air intake to stop the siphon. I'm going to mess with the drain pipe and add a bigger air break tube. If I'm on the wrong track someone please let me know. And if anyone knows of a better more reliable siphon technique please share. I just need help getting this to work so I can get started >.< all suggestions are welcome. I just want this siphon to stop already lol

Maybe you have to much water flow going into the bed. Try cutting the water flow down by diverting some of the water back into the tank.

Or I can just adjust my pump valve right? Too much water flowing in crossed my mind, having no gravel and such a large bed I tend to crank the pump with impatience. I'm going to try lowering the water flow when I get home

Normally, there are only a couple of things that have gone wrong here

1. Get rid of the break tube, Affnan design all the way
2. Media guard not allowing enough water through
3. sticking a 90 degree bend on the end under the GB helps
4. To much water flow
5. Not enough water flow

Thats about it i think

Thank you so much, my major concerns are my non level bed floor and the fact that it's only 5" deep max. Is such a shallow bed even worth it?

Personally I'm no fan of siphons even though I have had good results with them. I prefer running Constant Flood without siphons because you don't have the water fluctuations..

If you are certain you want to run with siphons then +1 from me for those who suggested Affnan siphon





I've used loop siphons and bell siphons but it's just so easy to run CF why bother with siphons?

I agree Scotty, my new systems will be CF but ive done a lot of siphons

What's your opinion on the plant results on CF vs using a siphon? And again, thank you all. I think I can get this figured out now but do you think my beds too shallow? It's roughly 5.2 sq ft and only 6" deep. So about 4" or 5" of water. I hear it'll work for a lot of things but I wanted to hear your opinions. And I apologize for not converting to metric, I'm on my phone. Whenever on my computer I'll be sure to make the conversions.

@twiztid_blunt - what pump are you using? You say siphon starts in 20 30 secs - so you're getting at least half your 25gals in that time (as rough estimate) So that's approx 25gals/m x 60 = 1500Gals/hour.

Normally we try to change the FT volume about 1 time per hour or better, so maybe you've got a really big FT? How much water are you wanting to put through the GB?

With a 3/4" outlet I think you're overwhelming the siphon - it isn't getting time to drain far enough for the air break to occur. Run the system for a while and just watch the water level - when it begins to drain, does it ever drop past your air tube? Does it drop at all?

My impression is this doesn't mean your siphon will not work in the system - with no media you have far more water getting to the siphon more quickly than if you have your media there. I think it's possible you would have solved this if you had media in there - it would have overflowed the GB because the amount of water getting to your siphon would be reduced by the media.

I could be wrong in this as I've never tried to run a system without media - maybe it DOESN'T slow down or reduce the amount of the water at all.

Ive seen quite a few shallow beds with great results. 6" is about 150mm. Freoboy's IBC system had a 150mm deep grow bed and it did really well.

I think if you had media in the bed it will fill even faster because there is less space to fill. Connect a 'T' piece from your pump outlet and redirect some water flow back the fish tank, this will help you adjust the water flow and the splashing water back to the FT will be added aeration.



Like this..

From all accounts, CF systems work just fine. That might be due to choice of plants or maybe it doesn't matter - I think it is the O2 getting to the plants that matters, but I've certainly heard of plants in normal gardening that die rapidly with constant wet roots.

From the comments I have seen, many of the CF'ers go that path because they either didn't get their siphons working or they thought it too much work to maintain. I haven't seen any comments that they chose it as a superior system, just that, after problems they found it wasn't inferior.

My personal choice is to have F&D, simply because I think it mimics real life more, but I also like the siphons - I like the basic physics they represent. Otherwise I could run a Timed F&D - against that however, I have a preference for running machinery constantly; almost all wear and tear comes in start/stop operations.

It would certainly fill faster but would the media slow the arrival of water into the siphon? I tried to reason that through and can make a case for both yes and no.