Return line: how big should it be?

[Dan Ponton]

I am having a problem with the bell siphons. I have a 2" pvs return line that is gravity feeding back to the fish tank. Some of the bells are working fine, but some are breaking to soon and only drain about halfway down.

I am thinking the back pressure created from the 2" line filling with water is causing them to break to soon.I will have about 10 half barrels draining into this line when all is done.

Also there is only about 2-3" drop on the line.

Should this be a 3" line?

Or I can also add a sump next to the pool and U siphon which will add some drop to the return.

[TCLynx]

A siphon breaking too soon actually sounds like the flow through the gravel guard or the gravel itself isn't fast enough to keep up with the siphon rather than it being a drain line problem.  See if the water can't move through the gravel guard as fast as the siphon drains it from the bed, then the siphon will use up all the water in the gravel guard fast and get a gulp of air and stop while the bed is still really half full of water.  This is why I like my mesh gravel guards, they really don't restrict the flow of water the way a pipe with holes does and it's so tedious to drill so many holes.

That said, I probably would have done at least a 3" line for that many grow beds, or maybe a couple drains since the more common problem is that if one siphon kicks in it may start other siphons prematurely.  Some Vents that come up from the drain line to above the height of the beds could help avoid that happening so much.

[David]

Hey Dan, I second what TC is saying but would like to add a "1-2-3 rule" that I use.  If it is 1" riser/stand pipe then it should be a 2" drain and if you are manifolding several beds into a central line then that should be 3" and vented at the highest point.  If you don't have a highest point then put an elbow there and turn it vertically.  This will prevent premature suction on all the beds down the line. 

Generally when a siphon breaks it is because air has entered the siphon and lowered the vacuum.  When it equalizes the drain will stop.  But since several of them are working I would check your gravel guards and make sure you have enough flow into the bell.  If you are using snorkel tubes on your bells then make sure you don't have any small leaks on them as well.  Also check your riser/stand pipe seals.  I've had pinhole leaks of air bleeding there before.  The only way to find it was with a stethoscope on the bell then I could actually "hear" it.  If you've got good hearing you will notice a faint "slurping" sound.  Let us know what you find out.

[Sahib Punjabi]

Hello Don,

Nice to see you and your "better half" on Saturday :-)

I agree with what TCLynx writes. In addition to that, looking at the picture that you have posted, I am wondering if there is an adequate drop in the drain line to allow a proper drain. Is it sagging in the middle of the blocks?

Love to know if your tried juicing the Aquaponics produce, especially the cutting celery. If yes, any thoughts / comments?

God bless

[Sahib Punjabi]

Don, I do have another observation. When I designed my systems in the wasteland area, I was really limited for space and placed my grow beds at the edge of the hoop-house. That actually does not allow for much growth area (given the curved hoops),, so it limits you to some extent as to what you can grow. If at all possible, I would suggest that you bring in the grow beds in the center and use the sides as walkways. This way, you can have greater flexibility in working the grow beds as well as reasonable height & ground cover space for plants such as pumpkins / melons etc.

God bless, 

[Dan Ponton]

I do hear a slurping sound in one of the beds... should I glue all the pieces together?

Community AP said:

Hey Dan, I second what TC is saying but would like to add a "1-2-3 rule" that I use.  If it is 1" riser/stand pipe then it should be a 2" drain and if you are manifolding several beds into a central line then that should be 3" and vented at the highest point.  If you don't have a highest point then put an elbow there and turn it vertically.  This will prevent premature suction on all the beds down the line. 

Generally when a siphon breaks it is because air has entered the siphon and lowered the vacuum.  When it equalizes the drain will stop.  But since several of them are working I would check your gravel guards and make sure you have enough flow into the bell.  If you are using snorkel tubes on your bells then make sure you don't have any small leaks on them as well.  Also check your riser/stand pipe seals.  I've had pinhole leaks of air bleeding there before.  The only way to find it was with a stethoscope on the bell then I could actually "hear" it.  If you've got good hearing you will notice a faint "slurping" sound.  Let us know what you find out.

[TCLynx]

Dan, Silicone might work to seal up the air leaks, if you glue, it's more perm.  If you are using the breather tube that is a likely point of air leaks getting in.  If it's just the cap on the bell, I would say a little bit of sealant might take care of the air problem.

[Dan Ponton]

I will check the sage in the piping. I already have a 2" stand pipe at the end of the line and that helped a lot.

I did juice the some of the cutting celery and the Swiss chard. We also used some cutting celery in a casserole. I got some hitchhikers in the roots of the celery. Little tiny shrimp or something.

Sahib Punjabi said:

Hello Don,

Nice to see you and your "better half" on Saturday :-)

I agree with what TCLynx writes. In addition to that, looking at the picture that you have posted, I am wondering if there is an adequate drop in the drain line to allow a proper drain. Is it sagging in the middle of the blocks?

Love to know if your tried juicing the Aquaponics produce, especially the cutting celery. If yes, any thoughts / comments?

God bless

[Sahib Punjabi]

 :-)

Well if they survived, put them in your system. They are the "Gammaurs" or shrimp like creatures that seem to occur in mature systems help clean the system. I know many Aqaupons look forward to such as in their systems. Here is a link to one such discussion:

http://aquaponicscommunity.com/group/green-acre-organics/forum/topi...

God bless

[Dan Ponton]

I checked the caps on the bells and many would leak water so they would leak air also. I was using test caps to save a little money and it caused me a lot of aggravation. I will replace them with pressure caps.

TCLynx said:

Dan, Silicone might work to seal up the air leaks, if you glue, it's more perm.  If you are using the breather tube that is a likely point of air leaks getting in.  If it's just the cap on the bell, I would say a little bit of sealant might take care of the air problem.

[Tony Gilliam]

Dan, i would try stagering the fill and drain cycle to keep them from all filling and then all draining at the same time. I think your drain line should be bigger if they all cycled at the same time. Try filling and draining one at a time then add more until they start shorting out to see if this is truely the problem. Take the time to fill and devide it by the number of growbeds you have then that would be the time inbetween opening the inlet valve. Hope this helps!

[TCLynx]

Tony, unfortunately there is no way to guarantee that siphon beds will stay staggered in their cycle times.  Trying to make sure siphons are staggered is going to be a bit like herding cats.

[Tony Gilliam]

TCLynx, Yea i know but it was a thought. Thats why i suggested a larger drain line. By the way, I've herded cats before, get rid of the horse and rope cause they come running for cat food. If you can't push it, then pull it. Same thought with herding cats. It can be done.