Pod-friendly pump?

[Anemone]

I'm looking for a pump to run in my refugium to add some circulation for a little experiment. Any suggestions for one that won't shred my pods? Looking for pretty low flow, maybe 10 gph with at most a foot of head. Can run intermittently on a timer if the pump is stronger than that. Main purpose is to move water and pods around. Any suggestions, hopefully not too expensive?

Thanks!

[L8 2 RISE]

You could try to use an air pump/pipe. Basically run air bubbles up a pipe which causes it to draw water. Never tried it myself, no idea how it would work, just throwing out ideas

[zygote2k]

look up "geyser pumps". It's like what Sam is referring to.

[Origami]

An air-lift sponge filter with or without the sponge might create the circulation you're looking for.  At the heart of it is an airlift pump: A pipe, an air stone, and an air pump. The bubbles rising up in the pipe create pressure that lifts water up from the bottom of the pipe, exiting it at the top. It won't lift water very high up, though (no real head pressure with small bubbles). A geyser pump is basically a pulsed airlift pump that uses a single, large burst of air to form a single bubble that lifts a load of water up through the pipe. 

[Anemone]

Thanks for the input everyone, I hadn't considered the simplicity of an air lift. The geyser pump is neat design I hadn't seen before. I'll look into availability or DIY options.

Some combination of air lift and geyser should cover most of what I'm trying for, but there is one place where air bubbles might be a problem. Does anyone know of another very Pod-friendly alternative? I say "very" friendly since I'd like the vast majority of pods to survive the trip. I'm assuming that the standard pumps probably shred a lot of pods, but I'll freely admit that this is only an assumption as I haven't seen any experimental verification on this.

Thanks again!

[Anemone]

So, I spent a few minutes on Wikipedia and maybe what I want would be an "axial flow" pump? Basically it's a propeller in line with a tube, with the flow running along the pump axis. Compared to the centrifugal pump design the pressure is lower (Wikipedia a gain), so (maybe) less pod death. I'll look more but if anyone knows about a small, salt water rated option that would be helpful.

[Origami]

My concern would be that the acceleration in prop pumps (or hitting the vanes) would most likely kill pods.  However, it does bring to mind an Archimedes screw which can turn much more slowly.

[Anemone]

You right of course Origami. Along those lines, maybe a peristalsis pump would be good here? More expensive than I wanted though, unless there is a really cheap or DIY option. Flow does not need to be precisely controlled so the quality can be much lower than the typical dosing pump. If only I had a spare lying around.

[Origami]

Not a peristaltic pump, because it pinches off the tubing and would crush anything caught there. Maybe some sort of diaphragm pump, though? I don't know. Is this for a fairly small system?

[Origami]

How much DIY are you willing to consider? Could you just put a prop/shaft combo on a relatively low speed motor (the motor would be out of the water) and use that for circulation?

[Anemone]

The water flow is modest. I'd probably run a pump for a few minutes per hour on a timer.

The DIY might be above my skill level.

Let's move the finish line a little. Besides airlift, any suggestions for the pump you would expect to kill the fewest pods? Very slow, weak output is fine, probably even preferred.

[Anemone]

How about a nano sized circulation pump with the business end jammed into a PVC tube? Something like a Hydor Koralia Nano pump (2" diameter) but even smaller.

[Origami]

How about a nano sized circulation pump with the business end jammed into a PVC tube? Something like a Hydor Koralia Nano pump (2" diameter) but even smaller.

If you put a large sponge filter on the front intake side- something with a lot of surface area, you could probably reduce the suction enough to where it wouldn't draw pods into the intake and shred them in the impeller...

[Anemone]

This will look pretty weird but that is what sumps are for. I wonder how much flow I'd get, that is really not what the engineers at Hydor were thinking about. Time to go play in the bath tub.

 

*knock* *knock* "Honey, what are you doing in there?"

"Um.... Nothing!"

[Origami]

Have you thought about just diverting some flow from your drain to the refugium section to get some more turnover in there?

[Anemone]

I'm trying something a little different. Might start a separate thread about it, but first I have to flesh out some things and think about whether the idea is too dumb to share.

[mogurnda]

A couple of thoughts.  First, based on my experience with pod infested tanks, and from the literature (which I am working on tracking down again), most small arthropods (cope-, amphi-, and iso-) have a relatively high survival rate going through centrifugal pumps, so I would not worry as much about that.  Second, if you don't believe me about the first statement, an airlift will indeed do the trick.  In trying to devise a slug-friendly circulation system, I have played a lot with airlifts, and you can get substantial, gentle circulation with just an airstone and a length of PVC pipe.  Two issues, though.  One is the obvious salt creep from the fizz.  The other, which is kind of obvious when you think about it, is that a length of tube with bubbles traveling upward can become a protein skimmer.  Not necessarily a problem, depending on the arrangement, but you can have a contraption that periodically belches out brown glop if you aren't careful.

 

I'm trying something a little different. Might start a separate thread about it, but first I have to flesh out some things and think about whether the idea is too dumb to share.

I dare you to share an idea that is half as dumb as some of my experiments.

[Anemone]

Great info, thanks. Also less messy than shooting water around to bathroom while trying to figure out how to attach a circulation pump to PVC.

Let me hold off on giving more details until I've got something closer to a complete thought.

[Jason Rhoads]

I too have wondered down this path. What I found was exactly what you have read in the above posts. Airlift, screw, different variety of pumps. . . all boiled down to: pods will make it through run-of-the-mill circulation pumps in numbers which are pretty significant.

 

I was working on a screw design when I decided it really wasn't worth it for my application. I am interested to see what yoiu are concocting!

[Origami]

A couple of thoughts.  First, based on my experience with pod infested tanks, and from the literature (which I am working on tracking down again), most small arthropods (cope-, amphi-, and iso-) have a relatively high survival rate going through centrifugal pumps, so I would not worry as much about that.  Second, if you don't believe me about the first statement, an airlift will indeed do the trick. 

Thanks for this. I was always under the impression, for some reason, that centrifugal pumps took a pretty heavy toll on many different pods. This is good to know. And good for them, too!

[Anemone]

It doesn't seem intuitive that pods could survive well but if they can make it through our high-powered pumps then something with lower flow rates and less head should be fine.  Thanks all.