Make your own swimspa?


I keep seeing free hot tubs on craigslist and wonder if I can put a couple to work.
I'm considering building an in ground, concrete swimspa next spring. Can the pumps, bubblers & fittings be adapted for use in a concrete enclosure? Will a pump- or 2- provide enough water flow to swim against?
Has anyone here ever built a concrete tub? I'm considering an 8x15 footer- maybe 5' deep? 4?
I'm still in the head-scratching and envisioning stage. Welcome all comments, criticism, or advice.
Thanks, Jim
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In the grand scheme of things, I don't know see that you're saving much to justify trying to salvage parts from free spas or how they can be adapted to a concrete spa. For example, in my spa, the air bubbler is nothing more than an air blower that forces air through hose and a passageway and out holes in the fiberglass spa bottom. How you would adapt or make that out of concrete, I have no idea. I guess the water jet portion could be fitted into openings in the poured concrete, but then you have the little details like the air for the jets is controlled by a valve device that controls the amount of air that can enter. That is built into the top of the spa where you can reach and turn it. How and where do you mount that in the new arrangement? Another issue would be the heater. The spas you're talking about have heaters that put out about 6KW. I would expect that concrete spas, because of size and thermal issues would require larger gas heaters. It would seem to me that to get anywhere near decent results you need a whole lot of experience and the right parts. Why not just get a regular spa?
Will a pump- or 2- provide enough water flow to swim

Oh, maybe this is why.
Sure, it will, if it's big enough. But the pumps in the typical spa do not move any where near that much water. They blast water out of jets and use 2" piping, which gives you a soothing jet of water, not a river current. To move enough water so that you can swim in place requires far more water than any of these pumps can supply. Though not popular, some people do have these types of pool.

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Funny you should ask - I have just such a pool almost completed in the basement of my new house. The size is 8' x 14' by 5' and the water will be 4.5' deep. The concrete work was done just after the basement walls were poured. The jets, intakes, light housing and skimmer were cast into the concrete. The pool itself is painted and the I am in the process of designing the pump and other mechanical system.
My preliminary design was for a 400 gpm pump for maximum current speed but the pump will be variable speed so I can have a nice slow speed for aquacize. The jets came with 1.0" diameter orifices and I also bought a set of 0.925" orifces so I can experiment.
Since the pool is in the house I do not want any chlorine smell at all and have investigated the options for disinfection.
It has been a lot of work researching and designing the varius systems. I will be getting help from some industrial engineers to design the control system.
I would be happy to discuss my work with you but I don't want to use my email address on the public group. I'll try your address to see if it connects.
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On Tuesday, August 19, 2008 1:35:48 PM UTC-7, Jim Elbrecht wrote:

Just wondering how your swimspa plans are coming? I would like to form a si milar sized concrete swimspa in the spring. I have 3 pumps / hot tub valves and some larger to start with. It seems you guys had it pretty well figure d so any advice would be appreciated, regards Nigel.
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