siphon problems

[carshaw]

Hi we have setup our beds with gravel and had the siphons working when the pipe just ran out to the ground with a continuous flow from the fish tank. Now that we connected pipes and are running them to the fish tank they continually run. We have tried adjusting the levels of the pipes where it goes into the tank but it's still not working. Any suggestions?

[GaryD]

Hi Carshaw,

Autosyphons will run continuously if there's insufficient flow through to the grow bed.......and they benefit from some back pressure at the point of discharge into the tank. Pictures of your set up might help to pinpoint the problem.

Gary

[Outbackozzie]

Your problem is the long continuous run back to the tank. You have to fit a preather to this drain pipe, near the beds. This can be a T-piece, which allows air into the drain pipe.

What has happened is your long run back to the fish tank creates a suction on the siphon, which does not allow it to break.

[carshaw]

Hi Gary and outbackozzie,
we have tried fast and slow filling of the growbeds (we have a pipe across the top with holes distributing even water along the whole bed) but this doesn't seem to make a difference.
Not setup yet for photos to the comp haven't installed the software, but Our beds are long 5.4m by 300mm wide and 150mm deep. We also tried the tpiece near the drain from the beds. We just either get it working and it does cut out but then it won't regain it's suction and pump again. Or it suctions but then won't stop. We just can't win????

[GaryD]

Hi Carshaw,

With your beds just 150mm deep, why don't you consider continuous flow rather than flood and drain autosyphons? Much simpler and no less effective when it comes to growing plants.

I'd consider running about 50mm of water in the beds initially......to give you a chance to determine the depth of gravel that gets moist. Once you see how far up the gravel the moisture travels (by capillary action), you can adjust the depth of water that flows through your grow bed.

You can feed the grow bed at one end and have the water flow to the drain end......or you can install a watering grid (a PVC pipe with holes in it) and plant your seedlings alongside the holes.

Personally, I find it easier to let the water run in at one end of the bed and drain out of the other end. Since your beds are long and narrow it should work a treat.

There are some people who believe that grow beds must be 300mm deep (I'm not one of them) so I'm keen to see your 150mm grow beds brimming with produce.

What are your grow beds made from?

Regards......Gary

[POC3442]

Gary,
I'm curious as to how high up you'd like to see the water wick up if it was a continuous flow system. Also, any suggestions for pump set ups for continuous flow? My main concern would be that one day the pump would die on me and I would be up a stream without a paddle and my plants would all die before I woke up. If I needed say 200 gph flow would I be better off using 2 100 gph and having them both connect to the same GB feeder pipe so if 1 crapped out there would be 1/2 the water needed but still some water and not complete failure?
Taylor

[GaryD]

Hi Taylor,


I'm curious as to how high up you'd like to see the water wick up if it was a continuous flow system.
Continuous flow systems take two forms.

One involves maintaining a permanent reservoir of water in the bottom of the grow bed. Water from the fish tank is introduced at one end of the grow bed and it flows along the length of the grow bed and drains out the other end and back into the fish tank.

Depending on your choice of media, you will get more or less capillary action. With clay pebble media, you'll get plenty; with gravel, you'll get less. Carshaw's beds are only 150mm deep (and he's using gravel as media) so, with some experimentation, he should be able to arrive at a water level which will provide adequate moisture to the plants without waterlogging them.

The other option is to set up a watering grid......made of PVC pipe with holes drilled at predetermined intervals......which is placed on top of the media. Seedlings are planted adjacent to the holes. With this option, the plant relies on the water issuing from the hole in the PVC pipe to irrigate the root zone of the plant.



Also, any suggestions for pump set ups for continuous flow? My main concern would be that one day the pump would die on me and I would be up a stream without a paddle and my plants would all die before I woke up.

I use the first option, so there's always a reservoir of water in the grow bed.....so the plants are never without water.




If I needed say 200 gph flow would I be better off using 2 x 100 gph and having them both connect to the same GB feeder pipe so if 1 crapped out there would be 1/2 the water needed but still some water and not complete failure?


As I already indicated, the lack of water for the plants is not an issue if you use the same method I do. In the event of pump failure, your idea would be good for keeping the fish going (they are much more likely to die in the event of pump failure) but in the event of power failure, two pumps would be of little use. In this situation, you'd be better off with a battery-operated back up system.......mainly in the interests of the fish.

Gary

http://www.aquaponicshq.com/forums/images/misc/progress.gif

[Bidadisndat]

Should've logged on as soon as I got home from work this morning - Gary beat me to it: Was thinking about your GB last night and figured that with such a relatively shallow bed, continuous flow would be the way to go. But then again, that's something I learned from Gary anyway. :D

(I'm an adherent of 300mm, F&D, Gravel Media GBs, but to each his live-and-let-live own. Like football codes, there's plenty of room for all, I say.)

[GaryD]

Hi,



I'm an adherent of 300mm, F&D, Gravel Media GBs, but to each his live-and-let-live own. Like football codes, there's plenty of room for all, I say.

I like them too. Where I differ with some folks is when they begin to tell people that grow beds must be 300mm deep when I can demonstrate that they don't........and that there are even some advantages to going a bit shallower.

Gary

[Bidadisndat]

I'd probably go shallower if I was going to have to pay the $$$s for clay pebbles. :D
Reminds me of when a friend of a relative asked him to give a hand loading up a trailer with blue metal one dark night: Turned out that the metal was coming from a stockpile that their local council had been building up for some job. Apparently quite a few people had the same idea, and the council was forced to erect a secure fence around the site. Our local council doesn't bother fencing off their stockpiles, but then again, they don't have piles of 20mm agg that could be used for GBs!

[Outbackozzie]

There are advantages in going deeper too - my 1m deep beds can contain a hell of a lot more plants than the 350mm barrels.

[POC3442]

There are advantages in going deeper too - my 1m deep beds can contain a hell of a lot more plants than the 350mm barrels.

Wow 1m thats just nuts! That being said I'd be curious if you wouldn't mind explaining how much closer or how many more plants you think you can fit in it with beds that deep. I would think that after a 1/2 a meter youd be able to have plants next to each other touching taking up every space on the grow bed.

[Outbackozzie]

With the smaller beds, they become root bound quite easily with overplanting, causing water flow issues. The big deep beds do not have any problems at all, even when very very heavily planted, especially with invasive plants like broad beans.

[POC3442]

With the smaller beds, they become root bound quite easily with overplanting, causing water flow issues. The big deep beds do not have any problems at all, even when very very heavily planted, especially with invasive plants like broad beans.

When u say smaller beds what size do you mean? I am looking at a 4x4 foot grow bed and am still trying to figure out my depth....either continuous flow shallow or deep F&D

[GaryD]

Hi,

At the end of the day, the whole bed depth issue comes down to what the plants need:

Water
Nutrients
OxygenIf you can supply all of these in adequate volume, then nothing else matters. The best way that I can demonstrate the relative unimportance of media depth is to point to nutrient film technique systems where:

Water = plenty
Nutrients - plenty
Oxygen = plent
Media Depth = 0I take OBO's point about using deep containers to grow some plants (for which his half barrels are excellent) but most high value plants (lettuce, Asian greens, herbs, tomatoes, cucumbers, capsicums) will grow in little to no media.

Of course, if you have little to no media, you will need to consider alternative means of providing bio-filtration......which is simpler and cheaper to provide than grow bed volume.

Gary

[POC3442]

Thanks Gary...as usual u know how to really clarify things that even a non-experienced bookworm can understand. Hopefully this week or next I'll be able to try and start cycling my system. Then fish later :)

[Outbackozzie]

When u say smaller beds what size do you mean? I am looking at a 4x4 foot grow bed and am still trying to figure out my depth....either continuous flow shallow or deep F&D

The smaller beds are the 1/2 barrels :


http://wa-donaghy.smugmug.com/photos/595099602_ysZYB-M.jpg
Around 350mm of media.

The bigger beds are the IBC's:

http://wa-donaghy.smugmug.com/photos/482105558_gFxvZ-M.jpg
Around 1m of media :D

[POC3442]

NIce pictures! I'm suprised with the corn you don't have it planted closer together. When we plant it in regular soil the corn might be 2-3 inches apart. Or do you run into root issues?

[Outbackozzie]

Was my first planting, I'll put some photos up later of what the IBC's look like now in winter, there's no room left at all :D

[AquaBybee]

I too am having problems with my auto siphons. I am thinking I don't understand exactly how they work. My GB are about 1 meter wide, 2.25 meters long and 230 mm deep. The water is distributed into the GB from a tee bar at one end. It has 5mm holes every 25mm along the bar. My auto siphon is centered at the opposite end of the GB. I have a 25mm stand pipe with a small hole (3mm) drilled into it at the bottom. It is 30mm shorter than the GB depth. The bulkhead is 25mm reduced to 20mm back to 25mm PVC pee trap then dumping back into the tank within 300mm of the bulkhead. The bell is a 70mm ABS pipe with cut outs around the bottom. I used a 40mm hole cutter and cut 6 holes around the pipe, then cut it in half to make two bells. The bell is 220mm high, sealed with an end cap at the top. I used a drip tee fitting mounted into the top of the side 25mm from the top, then a piece of 5mm pipe 170mm attached to the side of the bell. The bell is surrounded by a 100mm ABS pipe with a couple hundred 3mm holes to allow the water in around the bell. My pumping system fills the GB in about 15 minutes. The system was filling, starting the siphon then stopping about 1/4 the way down. I thought the gravel wasn't letting the water drain to the siphon fast enough so I added a half round ABS drain pipe down the middle of the bottom of the GB. It has about 1000 3mm holes in it. That didn't help. Then I discovered my air vent pipe, which I had cemented in with epoxy, leaked. I fixed that, but then the GB filled without the siphon starting at all. I then cut out the end cap and replaced it with a plexiglas window. Now I can see the the level inside the bell does not fill as fast as the GB. Am I filling the GB too fast? Is my stand pipe too tall? I would appreciate any and all advice you could provide. Thanks in advance, Grant

[nwestwood]

There is a good post around here somewhere that covers siphon problems. In my case they boiled down to 3 issues 1)in flow (to fast or to slow), 2) head space, 3) creating the siphon.

Flow to fast and the siphon never shuts of.
Flow to slow and the siphon never starts, it just trickles.
head space to tight - water can't build up velocity
head space to large - (haven't had this problem)

I also found that putting a flex hose on the outlet and having it curve up 1/2 to 1 times the height of the tube helps get the siphon going, something about the water pooling tube, causing it to seal makes a HUGE difference.

The air break tub is optional, but helps break the siphon when the tank empties.

My standpipe is 1" (sorry, don't know the metric equivalent),
My Bell is 2" and
the black corrugated drain pipe is 4"

I added lots of extra holes in the drain pipe so the water flows in freely.

the way my system is setup, the fish tank overflows into a 2" pipe which lays across the top of 2 gravel beds and into a DWC tank.

There is a single inlet into each gravel bed controlled by a valve. The KEY to having my system work is that the flow into the beds is fixed and whatever is extra goes into the DWC tank. Any variation in the flow into the beds is bad as the siphon will either not start or not stop. There is a good range in between but outside that range it doesn't work.

After I got my system "tuned" in 10 months I've never had a siphon problem.

Also, I have 2 different stand pipes, one that is taller that I use when I've planted new seeds and want the water level to raise higher. Then a shorter one (about 1.5 inches shorter) that I use once the plants are established to keep the top of the bed dry (it keeps the bugs and algae out).

Here are a few pics.

also more pics are on my website:

http://www.utahap.com/Utah_Aquaponic_System_Construction.htm