Can You Build a DIY Endless Pool for Under $1500?

hooktenpushup · Sep 4, 2017

Hello, is this stupid?
is this project possible, about 1,500 usd.
I know the key is evenly distributed flow, so maybe two small motors. Maybe add a grate?
this vid gave me this idea:

thanks in advanced if anyone reads this thread

mfb · Sep 4, 2017

I don't see how you would get relevant flow, and it will certainly not be evenly distributed especially in a small pool. Add the safety concerns of a propeller in a pool with a human and it looks like a bad idea.

anorlunda · Sep 4, 2017

I was about to say yes. But I agree with @mfb about the safety problem. Figure out how to shield the propeller first, then post again.

sophiecentaur · Sep 4, 2017

mfb said:

I don't see how you would get relevant flow, and it will certainly not be evenly distributed especially in a small pool. Add the safety concerns of a propeller in a pool with a human and it looks like a bad idea.

The guy has no fingers!
The proposal is just the same as a treadmill; good if you have limited space or no access to open spaces.
Safety would be an easy problem to solve with a simple guard. But the non-uniformity of flow would be a problem for serious swim training. A number of propellors, side by side would do better and then some vertical slots to reduce the turbulence. Perhaps some ducting at the bottom of the pool to feed water to the propellors. There's no end to the possibilities. Testing tanks in hydrodynamics labs can produce (expensively) very real situations but, for a simple cheap solution, why not a couple of propellors (guarded) and a harness and tether to the rear end of the pool would be something to work against. A force meter on the tether would give an indication of how hard he was trying. (I use "he" because I reckon a 'she' would have more sense.

)

hooktenpushup · Sep 4, 2017

i have a 3d printer

anorlunda · Sep 4, 2017

Nope, that's too easy to push aside. More like this.

Fervent Freyja · Sep 5, 2017

Not even just a safety issue. This setup doesn't look conducive to developing proper technique. The kid is being thrown off balance too frequently. I see a physical injury developing.

sophiecentaur · Sep 6, 2017

Fervent Freyja said:

Not even just a safety issue. This setup doesn't look conducive to developing proper technique. The kid is being thrown off balance too frequently. I see a physical injury developing.

That is certainly a valid comment about this ultra simple setup. You would really need some vertical slots and 'trunking' to eliminate the turbulence.
The technique is not unlike the skydiving simulation they provide for training, with a large fan, blowing upwards. That seems to do a reasonable job but, as it happens, my daughter hurt her shoulder muscles as she went unstable. Whether or not it would have happened in real free-fall is another question.

CWatters · Sep 6, 2017

Note the use of a 12V battery. Do NOT under any circumstances try to replace the battery with a mains adaptor or charger.

CWatters · Sep 6, 2017

hooktenpushup said:

Hello, is this stupid?
is this project possible, about 1,500 usd.

You can buy one ready made for less...

http://www.ebay.co.uk/itm/like/272592187632?chn=ps&dispItem=1&adgroupid=47677752950&rlsatarget=pla-328431025568&abcId=1058846&adtype=pla&merchantid=7329334&poi=&googleloc=9044886&device=c&campaignid=863276821&crdt=0

http://www.ebay.co.uk/itm/Swimming-Pool-Exercise-Swim-Jet-35/300671112634?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D1%26asc%3D20150313114020%26meid%3D51840c2aa0a54b3bb23e9e94765e6474%26pid%3D100338%26rk%3D1%26rkt%3D30%26mehot%3Dpp%26sd%3D272592187632&_trksid=p2141725.c100338.m3726

BillTre · Sep 6, 2017

Aside from the immediate concerns about safety and even flow, this is certainly a reasonable idea.

A water diffuser of some kind would make the flow more laminar, but there will always be resistance at the edges of the flow slowing that part down.

There are products that produce similar effects:
Aquaculture:
Living Stream tanks: Have a long tank through which water is pumped from one end to the other. The water is returned under a horizontal baffle to the end from which it can. One way flow can also be done with raceways, divided ovals, or on a curved path in circular tanks.

Fitness Equipment:
Water Treadmills

I would steal ideas about safety, where to put the pumps, and return flow from products like these.

sophiecentaur · Sep 7, 2017

CWatters said:

You can buy one ready made for less...

http://www.ebay.co.uk/itm/like/272592187632?chn=ps&dispItem=1&adgroupid=47677752950&rlsatarget=pla-328431025568&abcId=1058846&adtype=pla&merchantid=7329334&poi=&googleloc=9044886&device=c&campaignid=863276821&crdt=0

http://www.ebay.co.uk/itm/Swimming-Pool-Exercise-Swim-Jet-35/300671112634?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D1%26asc%3D20150313114020%26meid%3D51840c2aa0a54b3bb23e9e94765e6474%26pid%3D100338%26rk%3D1%26rkt%3D30%26mehot%3Dpp%26sd%3D272592187632&_trksid=p2141725.c100338.m3726

Those prices are very high, compared with cheap Trolling Motors, used for fishing. They are as little as £100 each (Google for a load of ads with prices). Buying a turnkey system is paying for someone else to fit a few bits together and put a table on them. As the OP has gone to the trouble of doing the initial job himself, I think he could get much better value by improving on the system he has already produced. Also, those advertised systems don't address the real issue of getting laminar flow where it's needed.

hooktenpushup · Sep 7, 2017

First off thanks for all the awesome feed back. All the information was immensely helpful.
heres some screen shots of a few different systems

Here's a 4 horsepower pump, not the greatest reviews, I've heard reviews saying they need up to 2 x 4 horsepower engines for an average swim speed. cons: consumes power and feels like getting hosed