Aquaponics--is passive circulation possible? Looking for ideas

A siphon only works if the outlet is lower than the inlet.  It is useful for getting over a higher obstacle in between (like the wall of a fish tank) but the end result is just transporting water downhill with gravity.  You will not be able to get water from the bottom tank back to the upper tank just with a siphon.

Maybe this will help Lauren,

Communicating vessels

The siphon pipes are just another method of connecting the tanks.  It doesn't matter (with water on Earth) that the tubes filled with water may go higher than the 'normal' levels of the tanks, or where the ends of the tubes are (as long as they are below the water level).  When water is added or taken away from one they will all reach the same level again, so this will need to be a continual adjustment, sorry.


siphon is a bit more complicated than you need to be, and I was surprised how poor some of the explanations on utube are......

So I’m kind of imagining a bigger version of this:

https://t.co/xs4RcaOHWY?amp=1

Only the ‘watering can spout’ is made up of siphon hose. And ideally you can get the water from the fish tank from the bottom of the tank (where it’s dirtier).

If hoses don’t work might be able to create a ‘spout’ with some piping?

Now we’re up to 4 tanks lol! But imagine if the fourth tank was actually a grow bed that gravity feeds back into the first fish tank. Then you’d get a final filtration before water is returned to the fish.

Haha imagine if you could do it with actual watering cans strapped to the side of the tanks, with a pipe from their ‘parent’ tank feeding them, and arrange it so they’re ‘shooting’ into the next tank. Caus the water gets a bit of lift being pushed out the spout. That would be cute!

Actually now what I’m thinking is... say you get 4 tanks set up just like that. Circulating and oxygenating via watering can power. I reckon your biggest risk is that now the water is actually circulating too fast to be cleaned properly. As in it will be being returned to tank 1 before it has had enough time with the plants.
So what i’d go for (especially if you don’t want any kind of grow bed ‘filter’), is one tank fish, three tanks plants. Then you’ve got loads of fish food and the water has more chance to be cleaned/diluted with fresher water.

I think you should try to replicate the watering-can video in real life before basing your aquaponics system on this idea.

Mk Neal wrote:I think you should try to replicate the watering-can video in real life before basing your aquaponics system on this idea.

For sure! This is all about brainstorming and experimentation right? Clearly I’m no physicist... do you think the vids a fake?

What about something like what these guys are doing?



It’s not passive (human powered), but I can imagine an idea where you rope pump it once a day to fill up your plant tanks, which then gravity feed back to the fish At a slower rate?

Limitations are how long it takes the top tanks to drain = how many times you got to pump it.

Maybe could have it also powered by wind and /or a little water wheel powered by the gravity flow back into the fish? Then you could just pump as a backup?

Sadly I don't think that the watering can video is legitimate. I'm pretty sure the video's creator has employed some video editing tricks and/or hidden pumps.

:/

John Rosseau wrote:Sadly I don't think that the watering can video is legitimate. I'm pretty sure the video's creator has employed some video editing tricks and/or hidden pumps.

:/

Awww bummer. Thanks John

I like the human powered pump.  I could imagine it linked to a bicycle to make it more ergonomic.  Our local weavers have set up a bicycle powered loom which is quite effective see for what can be done with a little ingenuity (you don't have to watch the whole video to get an idea).
Alternatively something similar could be like a perpetual bicycle pump pushing air around, maybe into a pressure vessel (balloon?) to store air and extend the bubbling. That might be trickier, since air is less easy to contain.
Not sure about the watering cans, looks impressive but I'm sceptical as well that it actually works for more than a few seconds.  If you get it to work let us know!

C. Letellier wrote:Now the thing you are missing is the temperature change per day the fish will stand without harm.  It is something like 1 degree per day.  The fish will have some temperature range they can live in.  Usually about 15 to 30 degree range.  But if you move the temperature by that much in a day the fish will be harmed or killed.  The amount of change you can have in any given day is a tiny fraction of that unless you want to make the fish sick or kill them.  Of course even if you could swing the full temperature range you are dealing with a really complicated system for it to work and the amount of fluid you can move passively is really small.  Likely not enough to support a single gold fish.  So the answer to your question I am going to say is NO.

Now a no moving parts system is possible under very special conditions.  If you had at least 3X the fall vs your lift height of a constantly running water with enough flow volume it could be done.   Use the falling water to power a Trompe pump to make air pressure so no moving parts there.  Run that thru an airline to an airlift pump and you have a system that will run with no moving parts.  The catch is the amount of height and large constant flow needed to make it work.  If you want to lift say 10 feet then the air pump will need to be at least 15 feet deep.  To achieve the air pressure needed to drive that the trompe pump will need roughly 30 feet of fall.

So far as I know this is the only no moving parts system that will allow true aquaponics.

Now there is a neat you tube video discussing why an airlift pump would be a better answer for aquaponics.  But they are still driving it electrically.  And the ways to make air pressure have more options but they are all complex in some form.  

Right now low voltage magnetic drive pumps are the other pump choice I would be looking at.  The one I got for the solar collector project has no external moving parts.  The rotor for the pump is the armature and it is all inside the pump.  No seals to fail.  It is a neat little pump with very little to go wrong.  And being DC I can run it off solar, off batteries or off AC power with very little trouble trading between them.

Now your other option is eliminate pumping totally, grow plants in the top half and fish in the lower half and fence them away from each other.  There are a number of you tube videos on this type of system also.  Most of these systems are bigger tanks though so one end of the tank can be devoted to letting the fish surface and feed etc.

On top of this, are you you intending to eat the fish as well?  If so, then you will have a much smaller selection of what you put in the tank.  Gold fish are not terribly tasty.  All of the bottom dwellers you mentioned to clean the tank will add to the bio load but not yield anything "delicious" for you.

Nancy Reading wrote:I like the human powered pump.  I could imagine it linked to a bicycle to make it more ergonomic.  Our local weavers have set up a bicycle powered loom which is quite effective see

for what can be done with a little ingenuity (you don't have to watch the whole video to get an idea).
Alternatively something similar could be like a perpetual bicycle pump pushing air around, maybe into a pressure vessel (balloon?) to store air and extend the bubbling. That might be trickier, since air is less easy to contain.
Not sure about the watering cans, looks impressive but I'm sceptical as well that it actually works for more than a few seconds.  If you get it to work let us know!

Nancy that’s awesome! I’m really into fibre crafts (spinning and crochet really but I dream of learning to weave one day too), and also building bicycles, so that video was pretty much the ultimate for me lol :)
I love that when people go to buy a scarf they can get on the bike and weave for a while 😂. So lovely.

Thanks for sharing :)

The biggest issue is that there is no proven continuous motion without some energy input.  The circular lift wheel for example needs either a water flow (stream) or a hand crank or small engine.  The other option is air power using a bubbler to lift the water which is how all the normal fish tank cleaner/ aerators work.
Aerators can be powered by a windmill pushing a bellows in and sucking out.  An example system is a "miller wheel" which is a double vane that has a small pulley on the spindle.  The best system would be a small solar system with an air stone bubbler to lift the water up and it can run to the bottom by gravity.

So I finally ran my first multiple siphon test, and at first glance it looked like a failure. I think if it was handled precisely right it would continue to flow, but I have this thing about breathing in water and couldn't get both siphons running...anyway. I'll continue to test that aspect.

After the water in the buckets had evened out (both hoses still full) I waited a while and then put a drop of food coloring in one of the buckets. It has now spread out to both buckets, the water in the second bucket is approximately half as green as the other, which means that something is still flowing. The buckets are still equally full. With apx 4 gallons in each bucket, does that mean that apx two gallons has been shifted, or perhaps 1 gallon per hour?

OK, you intelligent siphon people--what is happening, and how can I take advantage of it? It's entirely possible that I just THOUGHT the flow had stopped, but it was half an hour before I put the food coloring in and it's now been two hours since then. Two five gallon buckets with apx 3 feet of clear hose between them. I can't see any green in the hoses, but with a single drop of food coloring I probably wouldn't.

I think that you could achieve some degree of passive circulation with an air bladder in one tank. Atmospheric pressure drops or temperature rises, bladder expands, displacing water and vice versa. Level remains constant between two gravitated tanks, so as water is displaced in one tank, there will be flow away from the tank with the bladder. That's the only non-machinery (i.e. windmill), non electric option I can think of...


Personally, I doubt if you could achieve adequate oxygenation with any totally passive system to have any sort of stocking density or planting density. An airlift pump would be the way I'd go for a minimal input aquaponics system. Good oxygenation, can lift water a few inches with just like an aquarium bubbler...  

Hi,

As for fish able to survive on low levels of O2, catfishes are fairly hardy.  Of course the shallower your pond/channels the greater the oxygen exchange so you might want to tweak your depth to be as shallow as practicable for your fish.  Using a racetrack design might help with a wind-mill driven Ferris Wheel type "water kicker" something ultra light in construction, oriented with the prevailing winds, and large diameter so it can be moved by the lightest possible gust. Water is moved into a higher compartment and then trickle/gravity feeds through your beds and back to the fish.

I was just reminded that there was an international development project that built a kids playground and connected it a mechanical pump system, they used "kid power" to pump the village water.  Got kids? Harness all that energy. Build a free-access playground.

I wonder how well a thermal differential powered reverse siphon would do to both store excess greenhouse heat as heat, and also to do useful work to raise a small volume of water. Here is an example from youtube showing the concepts in action. He does use a fresnel lens to increase the heating  and decrease the cycle time, but if you did not care about how long it took (one daily cycle), I do not think the fresnel lens would be absolutely necessary. Then, just scale up until you get the volume you need lifted per day.



Another issue of applying this to aquaponics would be clogging or fouling of the check valves. Maybe need to combine with the "water teeter totter" idea given above to have some very clean water in the thermally powered reverse siphon side, and the "dirty" aquaponics water on the other side.

Again, this will probably not meet active oxygenation needs of any kind of serious stocking rate of fish. Though this may be enough to "passively" fill kratky buckets, make a very low flow NFT technique, keep duckweed tanks topped off, etc. But, all these tanks and flowing pipes and surface area will bring up the DO of your water a little bit as a side benefit. Picking fish species that can handle low DO is probably the best design choice.

This would probably pair better with vermiponics, which is where I think I am going next after this year's aquaponics experiments here anyway.

I love finding this thread when I'm perseverating on a simple balcony-scale system in the middle of the night. Human powered+ Quail manure + hydroponics + duckweed ... BSFL + compost.

Repurpose a large plastic bin I already have, situate it halfway under a children's table (ditto) for partial shade, scavenge some pea gravel, drill holes in some big Greek yogurt containers and try to create a cascading biological filter by propping them up at slightly different heights. I figure if I scooped a pitcher of water from below any time I feed quail, toss kitchen scraps or tinker in my balcony garden I could have a low key little system with a few indestructibles (mint, nasturtium...?) and a few fish or shrimp. It won't be hands-off like OP wants, but still sounds dreamy. Can anybody tell me more about preparing the poultry waste nutrients?

I kept a conventional ten gallon aquarium running for a decade with a pleco and a few little friends. (That gear went to Craigslist when I moved to Spain, but I have the basic idea on 'normal' fishkeeping is my point.) Any tips on an outdoor, manual system from experience is appreciated. Learning by killing swimmers is a drag. I wouldn't oppose a pump/bell syphon type setup, but it's lovely when you don't have to buy anything.

And/or show me the system you're currently running ;)

Some interesting ideas here. Things to think about. The thermal "pump" would only have to take the water up a few inches--less than a foot at the outside. Then the water falling back into the next tank would help to oxygenate the water a little more. It would be relatively simple to create the temperature differential necessary. He has the water just dribbling out of the hose at the top. Harness that power as well, to both oxygenate the water and drive water into the third tank.

Does this count as stacking functions? : )

You can not do it for two reasons.
First, there will be not enough of temperature gradient.
Second, if you have fish, you will need A LOT of oxygen, not just a pump, but a powerful one. Try going to aquarium store, give them the volume of your tank and ask whar kind of pump you need.
Sorry, but it always is that way.

P.S. Without fish, you can use some version of Kratky method, but fish wouldn't survive in Kratky tank.

I maybe so far off face, however, could you not use a system that you simply siphon to start? If the system is circulatory, as it would need to be, once the siphon is started it should just really just continue. So between gravity to get the water down and Synn to get the water back up, I think that would give you an input free system