siphon won't trip

[Anthony Vore]

I just started my first small system.  using 2 kids' plastic wading pools.  3/4 inch stand pipe with 1 1/2 inch funnel on top.  4 inch bell siphon.  water fills to appropriate level, then trickles until I jiggle a pipe. (sometimes the discharge pipe, sometimes the bell).  then it operates properly, draining until breaking the siphon at about 1 1/2 inches left at bottom.  Only thing I can think of is I didn't cut the bell pipe short, justed used the length I had. It's about 6 inches above standpipe.  I didn't want to cut up my last piece of pipe, and I didn't see where it would affect the siphon.

tony

[Randy]

Bell siphons can be finicky. Not enough flow and they won't start, too much and they don't want to break. So it is a good idea to follow the size recommendations carefully. Most would recommend a bell size of 3" for a 1 1/2" stand pipe and I would keep it about 2" taller than the stand pipe. For more detailed info try doing a search for "Affnan Siphon". 

[Jonathan Kadish NYC AA Chair]

Many people find that simply adding a 90 degree elbow on the discharge pipe or reducing from your 3/4 to 1/2 on the discharge will create the right flow dynamics you need.

[David Miner]

With a 3/4 standpipe, use 1 1/2 bell. use the 3 in for your media barrier. you want your standpipe to be directly in line with the bottom of the cap. you want your standpipe about 2-3 in under the surface of your media.

I have been running with this exact size for years, flawless from day one.

[Harold Sukhbir]

Hi Anthony,

The bell needs to be an inch or two above standpipe.

[Anthony Vore]

Thanks all/  I switched to a 1 1/2" bell with 1 inch vents (notches) on bottom, capped 2 inches above standpipe.  It worked a few times, then only kept a small constant trickle when full instead of siphoning.  I noticed from the bottom the discharge pipe didn't seem level and plumb, so I adjusted it and instantly the siphon started.  It has completed several cycles now, so thanks to everyone!!

[Averan]

Don't make your media guard smaller than 4", 6" if you can afford it. The guard has virtually no effect on the siphon but too small and you can't get your hand in there to do maintenance.

[Anthony Vore]

right.  I had scrap 6" black corrigated drainage tile I drilled 3/8" holes in. It works great and is easier to work with the smaller siphon.  The 4" siphon left so little room I couldn't even see the water level easily.

Averan said:

Don't make your media guard smaller than 4", 6" if you can afford it. The guard has virtually no effect on the siphon but too small and you can't get your hand in there to do maintenance.

[Jim Fisk]

FWIW, the water must pass over your funnel top evenly as you discovered. On one the size of yours I use a 2" bell pipe size and a 3" gravel guard and works flawlessly. The funnel being level is so important for a "trickle" as you describe. A bit more flow and it probably would have triggered as well. I have not had a 3" gap have any effect but 6" might be pushing it. Another note, make sure there are no leaks in the bell top. Glue well. When I started making my clear top bells in 3" I found it a bit of a challenge to seal the different types of plastics and it can take a few tries to get them sealed. I have to test every one before shipping. Nice thing is with the clear top you can see exactly what is happening right or wrong. Fun to watch too. and to make!

[Anthony Vore]

I used a 6" field tile corrigated black pipe for gravel guard.  It is nice because it gives me plenty of room to work. If this set up is problematic, I have room to take out the 3/4" standpipe and redrill and replace with 1".  At first it drained well, then as it started filling, at about 2" a steady trickle came through the drainpipe, then at 3" the siphon started again?  I had to imagine what was going on inside that bell (That clear top would be AWESOME. I'm adding a floating ruler inside the gravel guard to watch the water level).  Thinking that the pressure only partially equallized when the siphon got air, I visuallized a bell with water level at standpipe.  Maybe water in horizontal discharge didn't completely drain and only partially broke the siphon.  Putting a level on the discharge pipe allowed me to level it exactly and it seemed to empty completely on the next cycle.  You're right about the trickle starting with a faster flow, but I have a hard time finding a flow that is fast enough to start the siphon, but slow enough to allow drain to be complete enough to break the siphon completely.  One of the problems was that maple tree seeds and debris are falling into the water and clogging the pump flow so that it's not consistent.  I now have put the pump inside a collapsible wire fishing basket to screen out the bigger debris.  thanks.

Jim Fisk said:

FWIW, the water must pass over your funnel top evenly as you discovered. On one the size of yours I use a 2" bell pipe size and a 3" gravel guard and works flawlessly. The funnel being level is so important for a "trickle" as you describe. A bit more flow and it probably would have triggered as well. I have not had a 3" gap have any effect but 6" might be pushing it. Another note, make sure there are no leaks in the bell top. Glue well. When I started making my clear top bells in 3" I found it a bit of a challenge to seal the different types of plastics and it can take a few tries to get them sealed. I have to test every one before shipping. Nice thing is with the clear top you can see exactly what is happening right or wrong. Fun to watch too. and to make!

[Jim Fisk]

Hey Anthony,

I'm a picture kind of guy and if you would post some pics so I know what we are dealing with I (we) can be of much greater assistance. If you are using pools for GBs "2 kids' plastic wading pools" HOW BIG? Cubic feet of GB determines how big your siphon should be. A 3/4" stand pipe is good for half a 55 gal barrel GB but if you are in the 15 cf range like a 12" media depth in an ibc GB you should be in the 1" stand pipe range.

Post pics and tell us more, please. I need pics of details too like how you cut the bottom of your bells. I have seen some posted that I know WILL NOT WORK. Here is a quick pic of one of my "barrelponics" siphon bell, etc. to hopefully help you:I now use a router to cut better holes (and much faster in production) at the bottom of the 2" bell but that makes no difference in performance.

Pics please

BTW, the only maintenance I perform on the siphons is to rotate the gravel guard back and forth until I can make a full turn about once a month which cuts off any roots growing thru the slits. Then remove the roots that float up. That's it. So I use as small a gravel guard as fits and that results in more grow area. But you will need a knob to lift the bell, thus my blue or pink knobs. Also, I use a scrap of pipe in another corner to watch the water level in the gb so I know when it is about to trip. Nice to know and watch without disturbing the siphon.

[Anthony Vore]

these kid pools hold about 50 Gallons. The green outriggers I hope to use for tomato plants in wire cage.  I timed the flow rate with a stopwatch and gallon jug.  When the flow from the pump is about 1 gallon in 1min, 30 secs. it will trip the siphon.  Slower only trickles thru.  The siphon will drain the grow bed in 6 minutes.  It then takes 30 minutes to refill and start siphoning again. 

1.  Is this too fast of interval? Hard to get any slower and still trip the siphon.

2.  How high above top water level should the gravel be?  should I take the gravel bed down to even with the water level at high tide?

Seems to be working as long as I can keep the pump flow consistent. The first pump I bought was too small to start the siphon (200G/min).  The second pump I bought is too much, (900G/min.) but I used a ball valve to down regulate. I seems to slow down after a while and I have to open it up then reset the flow rate.

3. Is this hard on the pump to be choked down?  I can add a "Y" and split some flow back to fish tank for extra aeriation if I need to release some pressure.

Thanks. Tony

[Jeffrey Ihara]

definitely do not choke the outflow with only the ball valve. install the Y (like, immediately) and put the ball valve on the return to the sump. open the valve to reduce flow to the grow bed.