(for the record, I already attempted to ask this in the physics stackoverflow)

I'm attempting to create something similar to a vertical multi-siphon. The device would pull water from multiple sources, at multiple elevations (a total range of about 5 feet) up to the top source so it can redistribute down again.

This could be simply accomplished by (a) pump(s) or a mini-turbine, but the transfer medium should be about 4 inches diameter: about large enough for a Betta fish to move up.

I can't use a multi-siphon going down and just out-pump the down flow of water, this means the fish would have to fight against the current up the piping so this isn't really an option.

Chemical and thermal lift are also not feasible to move the fish.

I'll take you quickly through some research. Anyone reading this knows that (after priming) a siphon attempts to equalize pressure which equates to leveling out the water involved. enter image description here

While I can't find any examples of this, reason should stand that with a sufficient priming force, you can pull from multiple sources. enter image description here

You should even be able to do crazy things (to a point). enter image description here

So when you attempt to siphon vertically, it requires a pump. enter image description here

And it stands to reason that a (properly calibrated) pump system could be used to supply multiple sources. enter image description here

So the question becomes, how do we safely lift a fish that went down a siphon back up to its original level? enter image description here

The only thing that is currently coming to mind, is use airline tubing connected to a pump to pull the water from the point at which the "siphon" was primed.

Continually applying negative pressure might be enough to pull the water at a rate that isn't going to vacuum a fish. Though, I'll admit I'm concerned it might need a series of pumps like this to imitate a caterpillar propulsion system.

  • $\begingroup$ a water wheel taking buckets of water up - least damage to the fish as little pressure change and lots of space for them. $\endgroup$
    – Solar Mike
    May 15, 2020 at 19:51
  • $\begingroup$ Clever idea, but fish is likely jump out which become lethal the farther away from the source it is. And I just don't have room to add it....just noticed my pictures are gone, will fix. $\endgroup$
    – Kamurai
    May 15, 2020 at 19:54
  • $\begingroup$ Just knew you were going to object - that is why I did not make it an answer. And, just for you to think, why do river authorities specify fish ladders? $\endgroup$
    – Solar Mike
    May 15, 2020 at 19:56
  • $\begingroup$ Those are (usually, to my recollection) larger fish that are used to jumping legitimate distance. A Betta might jump a couple inches on a cascading tank situation (good aquarium idea, thanks), but it is very unlikely guppies will be able to clear more than an inch. Part of the reason for the requirement was to create a "fish elevator" as demonstrated in the pictures. $\endgroup$
    – Kamurai
    May 15, 2020 at 20:03
  • $\begingroup$ Try building a syphon to take water up and over a 4 foot wall using a 12" pipe. Let us know how you get on. And, I'll be interested as that was what we had to get water out of the reservoir into the water supply system and power the water turbine for electricity. Drawing it on paper is one thing - trying it for real is another. $\endgroup$
    – Solar Mike
    May 15, 2020 at 20:08

1 Answer 1


A Venturi pump may do what you're looking for:

venturi pump diagram

The pictured pump is for air, but the principle works for water too.

There are inline types that don't change diameter from inlet to outlet, but I haven't seen one of this type for use with water. I'm sure it could work for a small elevation gain.

For higher head pressures the water jet could be harmful to the fish, but in that case you could use multiple Venturis?

Another option would be to build some kind of "airlock" mechanism, that allows the fish to get into the up tube after the pump.

Or you could use a ram pump in reverse, where you pump upwards and then stop suddenly. The inertia of the water would cause some brief suction at the pump end which could suck a fish through a one way valve. One issue with this is that it would be hard to make a valve that would not injure the fish if it didn't make it all the way through. Maybe some kind of soft orifice?

  • $\begingroup$ I've used a PVC tee to make a hot tub cleaner. A slight angle to the injected water and the opening pulled great volumes into the tee and into the mesh collection bag. A fairly small volume injected at suitable pressure will move quite a bit of water. I think your idea has great merit. $\endgroup$
    – fred_dot_u
    May 16, 2020 at 0:00
  • $\begingroup$ This has a lot of good suggestions and moreso, they're ones I can research. Thank you for such clear thoughts. $\endgroup$
    – Kamurai
    May 16, 2020 at 17:19
  • $\begingroup$ I think adding a grated ram pump above each entrance to the shaft and then feeding all the output to the top level and letting the waste water flow back to the current floor might have some real merit. $\endgroup$
    – Kamurai
    May 16, 2020 at 17:23
  • $\begingroup$ After consideration, the Ram pumps won't work as they'd be indiscriminate on direction, I'd essentially trap the fish at the top of the elevator. Some sort of Venturi pump has to be the answer, and J. Ari might have put me on a path to find a commercial product. It just has to not kill the fish on exit. $\endgroup$
    – Kamurai
    May 18, 2020 at 13:32
  • $\begingroup$ The major caveat seems to be that the only exit (not against the current) is at the top where the water stream would have to be to draw the currents from the other levels. $\endgroup$
    – Kamurai
    May 21, 2020 at 13:13

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