I guess its theoretically possible...but there is a lot of undesireable stuff in sea water you don't want in your pool....like plankton. And they say that black algae normally comes from the ocean.

Also, you might want to check on the other inorganics that are present in sea water....http://www.seaagri.com/seawateranalysis.html
The inorganics don't look too bad since you will dillute that stuff out.

I would worry about the "living" stuff. I wouldn't do it...but I don't live on an island.

Sounds really cool but I see it as a potential water nightmare. Sea water is 10x the salinity of your average SWG but I guess you could dilute as needed.

If you could run the pumped sea water through a sand filter first and then blast it with about 10ppm chlorine, that could work.

What about the dissolved solids? Might need a chelating agent also.

I'm on the East Coast of Canada and we must have 5 or 6 customers that use ocean water for their pools. During the opening we just walk our submersible pumps down to the beach and pump the water into the pools. These pools are 100% ocean water.
If you plan to use a salt system on such a pool you have to use one from AutoPilot as they are the only ones that operate at salt levels around 40,000 ppm.

I would definetly shock the heck out of the water coming in....kill all the living stuff in the water....theres even the organisms that cause barnicles in there and they are very tiny non observable to start off with. Some of that stuff can live in brackish water and the last thing you want is barnicles on the side of your new pool plaster.

I don't know how it is done, but many pools in Europe are filled with seawater. We stayed at one hotel in Greece that had a *sparkling* beautiful pool full of filtered seawater, but it was very, very salty. These pools I'm sure are specially built somehow and I'm sure your standard pool in the US isn't able to handle seawater.

This same hotel also had one of those plants that turns seawater into drinking water (I forget what it is called) - again, very common in Europe, particularly in the Mediterranian areas that get so little rain.

There is no way a standard heater can handle 40k in salt. Let alone anything else metal. They do make high salt heaters but that seems a bit much.

As far as the idea in general, cruise ships have done it forever and they seem to have no issues with it.

Having toured the mechanics of a cruise ship, they are constantly exchanging the seawater via a inlet filter and heat the water going to the pool via a titanium heat exchanger with waste heat generated by the onboard power supplies.

Thats how they can dump and refill the pools so easily (nights and high seas)

cool stuff

Thanks to all who have responded. Please note that I am not talking about a seawater pool - I am simply talking about adding enough seawater to a freshwater pool to provide the salt for the chlorine generator.

As long as you address the other concerns on here about microorganisms and your dilution calculations are correct, I cant see where there would be a problem. If possible, test the water before you use it. And obviously, just make sure your pump pickup is suspended in the water and not sucking crap off the bottom when it comes time.

OK, thank you all again for all contributions.

I'm thinking that if I include an inline cartridge filter (to remove any particles) and an inline ultraviolet (UV) water sterilizer in the pipe to the pool and pass the seawater through the two while adding it to the freshwater in the pool, that should do the trick re concerns people have mentioned above (microorganisms, minicritters, etc.)...?

Once set up, it seems like a kinda neat way of adding the salt needed for the SWG....

Any member's further thoughts on the idea would be much appreciated...