Backyard Aquaponics
A place to discuss aquaponics

So here's the full system. http://youtu.be/jwIKUP4gfCY Still messy as it's not fully operational yet. FT is 150 gal. GB is whatever a 5'x5'x3'x12" deep "L" shakes out to.

Problem is that I can't get the siphon to break to save my life. Read the Siphon thread in Hardware. Even picked up on the lowering of one area of the standpipe to assist with the kick start for lower flow rate. But even with ZERO flow the siphon starts to break and then just dies leaving X inches of water in the bed. Hence the largest 3" cut in the bell that you'll see.

So here it is:

1" drain

6" downspout under bed - 90* elbow - 14" straight run to the sump.

Standpipe is 7 1/2" tall. 1 1/2" to 1" reducer on top.

Bell is 3" pipe. 10" overall length.

Siphon has no problems starting. Simply won't stop.

I previously played with a 2" wide siphon but had to flare the standpipe myself as the plumbing world has apparently gone batty and abandoned the "Nibco" style/funnel shaped reducers http://www.homedepot.com/Plumbing-Pipes ... PrUIvKANnU

Even with a snorkel on it THAT still wouldn't fully break either. So at this point, I'm down to swearing at the squirrels running through the back yard... Any suggestions are greatly appreciated.

take it out and go constant flood, I had bell siphons on my system for about 6 months and they would run great for a while then I had to fiddle a lot with the flow and I ended up pulling the bell out which its been running like that for two year and its so much easier

Your gravel looks a bit small

My guess is that it is leaving so much water in the bottom of the growbed because of the 2 slits up the side.

One option to break the syphon at the desired height is to have a tube running from the bell, down the side of the bell to roughly the desired height. When the water drops below the level of the tube it will start sucking air and break it.

I am not a syphon guru though, my thoughts with the syphon is exactly the same as wildfires. Each to their own though.

Check these mad paint skills!

Your cut is way to high. It needs to be very low, because it will suck air before the water level in the entire grow bed is at that level. It takes time for the water to get through the rocks so the water at the siphon is going to be lower than the water far from the siphon. My cut is only about half inch tall, and when it breaks I still have over a inch of water in the grow bed. There is no reason to switch to constant flood, or to use a tube. I have 6 siphons running for over a year now and have no trouble out of any of them. Some are more than 20 feet from the fish tank they dump into.

I have no issues with siphons - been running them for 4 years

Your cut is way to high as suggested. Dont worry about a break tube, its really not needed these days, they work flawlessly (for me anyways)

Break tubes give you adjustable height without having to recut the bottom of the tube; just push or pull the tube a little and run a cycle.

I'm not sure what Fishbits is saying though - there seem to be contradictory statements, vis-a-vis and

If I have this right, it's a flow problem as well as a height problem - with zero flow into the GB, the siphon begins then stops as soon as the high cut level is reached. As expected that's going to leave 3" or so of water in the GB.

With flow coming in the siphon doesn't break or stop - that sounds like the input is balanced or over-balanced with the output - i.e. the standpipe is not big enough or some of the flow into the GB needs to be diverted, perhaps back into the FT to create a swirl in the tank.

I'd redo the bell with small cuts around it (too small for media to get in) add the break tube then clear a space around the bell so I can watch the water levels and start the pumping. I'm thinking the water level will rise until the siphon starts and then it will not fall enough to clear the tube to break the siphon.

You can then check the siphon works by lifting the break tube just clear of the actual water level. Then it is just flow adjustment or make your stand pipe bigger in diameter to out do the input..

For flow - If the siphon will not start there is not enough water flow.....if it will not stop there is too much.

From the OP I presumed he filled the GB till the siphon started then turned the pump off to see what happens, so I'm betting with the pump on he's got too much coming into the GB.

*grins* Or maybe he's onto something with blaming the squirrels?

Hey, Fishbits, what size is your pump?

Thanks for the input, folks. As for pumps, I'm running a scavenged Intex 400 +/- GPH pol pump controlled by a piggyback float switch. Flow into the GB is knocked down by the position of an elbow in the swirl filter and a ball valve dialed down. Towards the end of the cycle in-flow to the bed is **significantly less than outflow almost to the point of zero on it's own.

What I was attempting to convey was that the siphon would start up w/o any problem and then, once started, with flow into the GB manually cut to zero, the bed would drain until the siphon would simply stop sucking water. It would gurgle a few times when the water level got close to it's low point but the suction would never completely break.

As the bell in the pic wasn't working as it was I decided to experiment with higher cuts in it which, as predictable, only lessened the volume of water that it would suck out of the bed before simply quitting. FWIW, the "triangle" cuts are the original cut size that I went with.

I've since made a new siphon tube with identical triangle cuts. This time, however, I've drilled a small hole approx. 1/4" above the cut line to see if that would introduce enough air flow to break the siphon. So far, it appears to at least **lessen** the suction enough so that once the GB starts to flood again. the back pressure from the in-flow seems to help release the suction.

What puzzles me, though, is that I have yet to experience complete suction loss in a siphon with either my 2" bell with snorkel or 3" bell with drill hole. Neither have the cap cemented on so they can't possibly be completely airtight but even if so, one would think that once enough water was suctioned from the GB the siphon would break - especially with the snorkel or drill hole. Any ideas as to what am I missing?

Ahhh so you are hoping to run your pump constantly then?

In that case, your pump is too big or your syphon is too small. Adding the tube to the top of the bell might help to break it by allowing more air to suck in at the low point.

Not constant, rsevs3. That's what the piggyback float switch is for http://www.pexsupply.com/Zoeller-10-003 ... ch-15-Cord . Kicks on when the water level rises in the sump. Turns off at it's low point.

If you stop the pump though, the water must stop flowing. It is just taking a while to break and stop gurgling?

It may just be a case of your media, being as small as it is, cant flow the water to the siphon fast enough for it to break cleanly.

So the point of siphons is so that you can constantly run the pump. I agree that the media looks too small. Also, people often forget about the media guard when troubleshooting siphons. Make sure it is not blocking too much flow.

Media is 3/4" pea stone on the surface. About 3" down it bumps up to 3/4"-1".

Ronmaggi I was thinking that the media guard might be affecting things myself so before I switched to the 3" bell I yanked it and drilled holes all the way around and 3/4 of the length. Watching the flow with the bell out things appear to come in and go out fairly well.

Seems like I've got it solved now with the hole drilled. Soon as I can size the pic I'll have it up.

I agree with the other guys. If it is not breaking then you have to much pump. You can divert some of the water flow back to the fish tank, or you could increase the size of your siphon. I am running 1 inch siphon with 2 inch adapter on top on 4 grow beds with a 2k gallon per hour pump, and I have to divert some water away or my beds will not break siphon.