Siphon Down to Ground and Back Up to Tank?

[hawkiye]

Folks I have a question. I have 3 grow beds that are higher then the fish tank for gravity feed but I cannot run the drain pipe straight downhill all the way to the tank I need to run it down to ground level and over to the tank and then back up and into the tank. You can see my build on my other thread here: I am building a system - Update 5/5/13 (http://www.diyaquaponics.com/forum/showthread.php?1694-I-am-building-a-system-Update-5-5-13)

Has anyone done this? Theoretically it should work since the height at the other end of the drain will still be lower then the grow beds but I was just wondering if it might cause to much back pressure so it won't siphon? The water will need to go back up maybe 20"-24" to get back in the tank. I will run down hill as far as i can before going to ground level but it may be about 3 feet at ground level before it needs to go back up to get in the tank. Thanks ahead of time for any feedback. ;)

[badflash]

Sure. As long as the end point is lower than the source, it can work. You need to find a way to draw a vacuum at the high point, then no worries unless something plugs up.

[hawkiye]

Sure. As long as the end point is lower than the source, it can work. You need to find a way to draw a vacuum at the high point, then no worries unless something plugs up.

Thanks, not sure I understand what you mean though. Shouldn't the siphoning action keep a vacuum draw until the siphon breaks? Any suggestions on how to do it? Maybe another down spout at at the high point?

[davidstcldfl]

Great question hawkiye.
A 'regular' drain would work for sure.
I'm not sure, seeing as how it's a 'bell siphon' drain. Your right, the back pressure 'may be' too much....'?'...It'll be interesting to see if it works.

You didn't mention, will each media bed have it's 'own' drain line ?
You might consider a common header that all the media beds drain into. That would eliminate the possible back pressure issue.

The 1st time I tried to do this, the header was too small and if one bed was draining, the others couldn't start.
Then I over sized the header, so there would be more then enough room for the water, in case more then 1 bed was draining at one time.
When a bell kicks in, it's surprising how much and how fast the water comes out. Especially when using a 'affnan' style bell siphon.

[badflash]

A bell siphon won't drain up hill. It would add air to the drain line each time it cycles. It might be possible to set up an intermediate tank that the others siphon to, and put a bell siphon on it. Give us a sketch of your setup and maybe we can come up with a solution.

[badflash]

OK, I saw your post on the build. The bottom of the bell siphon needs to be above the highest point of the drain. Back pressure may keep the siphon from "kicking" even then. Best to figure out a way that the drain line is empty.

[hawkiye]

I guess the only way to find out is to try it and see. I would like to use a common drain pipe too if possible. I am now thinking maybe if I use poly pipe with no elbows till it gets to the tank that might reduce the back pressure enough to get the siphons to kick. I really don't have the room for an intermediate tank between the fish tank and the grow beds.

davidstcldfl so you're suggesting maybe timed drain instead of bell siphon? I was thinking a bell might have more vacuum but you're saying a straight drain would be better?

I am not to the point of testing yet I am still working on my tank but hopefully sometime this week or next week at the latest I can begin testing. However I think I'll just try it play around and see what works. Thanks for the feedback and more suggestions welcome!

[davidstcldfl]

I looked at your picts. It looks like the bottom of the media beds are a lot higher then the fish tank...which is the ferro cement tank...?..right ?

I'm nor getting a clear picture of your lay out. Am I understanding correctly....
-there is no sump tank ?
-Why can't the media beds drain back into the fish tank ?

I guess I need a drawing.

[hawkiye]

Yeah the ferro cement tank is the fish tank the pipe needs to cross a walk way with a step in the patio so I would be blocking the walk way to take the drain straight to the fish tank otherwise that is what I would do. it is limited space on the patio so I had to put the tank over there. I am also thinking a common drain might not work since the siphon is under vacuum till it hits the drain it will have to push the water back up to the tank.

[davidstcldfl]

Ok, the drawing is a little rough. But, hopefully you'll get the idea....

http://i931.photobucket.com/albums/ad157/davidstcldfl/displacementfordrains_zps30022755.jpg

I've done this a few times and it works fine.
You can see each media bed has it's own drain ( whatever size you decide) and they drain into a 3 or 4 inch horizontal pipe.
I use 4 inch drain pipe for the horizontal and just use a hole saw, to make an opening for each bell drain to go into. I just stick the bell's drain in about an inch.
I reduced the rest of the common drain to 2 inch, after it turns downward.

You'll be able to go under ground and come back up...as long as the bottom of the grow beds are higher then the top of the fish tank.
The water isn't being 'forced' through the drain pipes. It's being 'displaced' by in-coming water.
The lower sections of the drain will always have water in them.

Consider using ( DWV) drain fittings, they have a radius to them. Less chance of them plugging.
It didn't show up on the drawing after I coppied it, but I had a cleanout (female adapter with a threaded plug) on the 4 inch horizontal pipe, to the left of the grow beds.
Time for a trip to the home improvement store... ;)

Edit...I just noticed your in Idaho, you have a frost line and all of that to worry about. You'll need to figure a way to remove enough water where it doesn't freeze in the winter.

[SimonB]

Hi!
Yah, that should not be a problem as the inlet is higher than the outlet! what kind of flow are we looking at? you have one huge pipe there :)
br,
Simon

[davidstcldfl]

Hi Simon,

Yes, the 4 inch horizontal pipe is pretty large.
The reason is, if more then 1 bell siphon kicks in at one time, the header has to be able to have more then enough room to handle the flow. It's surprising how fast the water comes out of a bell siphon...especially when using an 'Affnan' style bell set up.. :o
I experimented using a smaller common header and it didn't let a second bell (or third) to start, if one was already flowing.

The 4 inch 'drain' pipe ( thin wall pipe) here in the US is pretty cheap anyways.
I figure, it's cheaper to over size, to start with, then to tear it out and re-do it... ;)

[badflash]

A while back someone posted picks of a system where all be beds were interconnected by pipes at the bottom. Only 1 tank had a bell siphon that drained from a different penetration so there was only a single return line. That fixes most of the issues.

[hawkiye]

Awesome davidstcldfl you nailed it Thanks a million! Although I don't know that I will be going under ground I can run the pipe on top of the ground and under the toe kick of the step however I have considered going under ground to make it more astetically pleasing (but that is more work LOL) As for the frost line I am going to build a green house over the whole thing so not a problem.

So does reducing the pipe to 2 inch help with pressure at the outlet? Also I have one grow bed seperate from the other two as there is another walk way so it would have a seperate header and down into the two inch pipe. So wondering how to do that?

here is what I had in mind I am just wondering if you think this will work?

http://photos3.meetupstatic.com/photos/event/3/6/6/2/600_218233922.jpeg

This might give you a better idea with what I am working with definitely not to scale LOL:

http://photos1.meetupstatic.com/photos/event/5/2/b/4/600_218241172.jpeg

[davidstcldfl]

Yes, what you drew looks like it'll work.... :)

I only drew it underground, to show it would work, even under those conditions too. Good point on the aesthetics, if you think it's worth the extra work.

I used the 2 inch, to save some on the cost. Simple as that.... ;)
So far, the systems that I've done this on, are working fine... :)

[hawkiye]

Thanks appreciate it. Do the drain headers need an air vent in the ends?

[davidstcldfl]

Yes, the header needs vented... :)

On the 4 inch header, I make a hole for each media bed, with a hole saw. The small drains from each bed fits lose, in the hole. That's normally enough venting.

[hawkiye]

Yes, the header needs vented... :)

On the 4 inch header, I make a hole for each media bed, with a hole saw. The small drains from each bed fits lose, in the hole. That's normally enough venting.

Cool thanks! I was thinking I could get way with all 2 inch drain headers since I only have 2 grow beds on a common header and one on a single but connecting on the ground or is that pushing it? what do you think?

[badflash]

I had a similar system, and it needed high point vents. T the common line before it drops, put in a T and have the vent go up above the growbed.

[davidstcldfl]

Badflash made a great suggestion about venting.

Try it your way.

[hawkiye]

Another question guys. ;) I have an intex external pool pump for the 8' pool can I run the intake line over the top of my tank wall and down into the tank or better through the side about midway down? and should I run pipe down towards the bottom or just midway into the tank? I was hoping to get some water flow by putting the inlet on end and the return from the GB's at the other end. I need to know because the wife decided I need to face the tank with rock so i need to make the hole now if it would be better to have it through the side. Thanks in advance...

[rangebob]

I need to do something like with with some NFT tubes that I'd like to build for lettuce and strawberries. Would this work without a bell siphon?

[rangebob]

I'm following up that it does work if you place the return underground. I'm assuming as long as the feed side (NFT Tubes) is higher than the return (fishtank) than this will work.

[badflash]

Some types of lettuce work well, I can't say what strawberries will do.


I'm following up that it does work if you place the return underground. I'm assuming as long as the feed side (NFT Tubes) is higher than the return (fishtank) than this will work.