Our new pool under construction has an auto fill system. However, the local water co receives most of its water from canals/etc that cross great distances and pick up calcium and other minerals along the way. End result is that the default hardness of any water entering the pool would be extremely high (up to roughly 300ppm, or ~17 grains per gallon). To avoid a long term maintenance nightmare, especially with regard to cleaning the salt water system cells, I'd like to put something in to reduce the hardness before it enters the pool. My pool builder has told me we need to avoid a general water softener as that might be detrimental to our pebble sheen. Is there a standard solution out there for this? Something that would be easy to maintain and that we can use w/ reasonable cost over the 30 year lifetime that we expect to own and operate this pool?

Not really. Most people who live in areas with high CH levels just learn to adapt to living with higher CH levels in their water. It can be done with close attention to one's CSI and adjustments made to TA and pH, as needed to keep the CSI within a reasonable level. You may also check into the availability of reverse osmosis services in your area. They are able to bring a truck out to your house and "process" your pool water in such a fashion that they are able to pull out excess CH and CYA without replacing water.

As far as adding water to your pool and reducing the hardness on your own, of course, a water softener would do this but they are not designed for filling pools. They just can't process that amount of water that quickly. I see no reason why it would harm your pebble sheen. What will harm your pebble sheen is a pool with a CSI showing a high degree of potential to scale.

My water softener at our last house would process 800 gals of water before needing to regenerate and it wasn't a particularly large softener. I don't see filling a pool from scratch as being practical but I think a large Softener should be able to keep up with a few hundred gallons a day for topping off.

You would add some salt though so that could become problematic depending on your ratio of water loss due to evaporation vs splash out

Pool Services Tech here in SD offers the RO treatment.

Can you pool builder bring in water from a different source?

My tap water is practically soft water in my neighborhood.

Using a water softener is totally fine as long as you test your CH level occasionally and adjust it if needed. If you were to use 100% softened water to fill the pool and didn't add any CH manually you could have a problem. As long as you test the CH level occasionally and mix in a little unsoftened water as needed to maintain the CH level (or add CH when needed) there will never be a problem.

Salt accumulation from the water softener is only an issue with the most extreme source water hardness levels (which mean more salt added by the water softener). You want to keep the salt level at 5,000 or below. That will usually be very easy to do, but if you use a water softener it is a good idea to test the salt level two or three times a season or so just to make sure.

The other two approaches, besides using a water softener, are to replace most of the water in the pool every one to three years, or to get reverse osmosis treatments every one to three years. The frequency of treatments/water replacement depends on how quickly CH levels build up in your specific situation. Broadly speaking, all three approaches come out at about the same total cost, though that will vary from place to place and pool to pool somewhat.

A small RO system such as this might be enough to maintain water level. It is only 100 GPD but you shouldn't need much more than that. It could just run 24/7 and let the autofill make up the rest which should not be much.

Usually those small systems are not designed to be run continuously. I did a quick check and didn't find any duty cycle stats so it may be fine too. Wouldn't you want to put this or whatever solution inline with the autofill though?

Keep in mind that small RO systems throw away several times as much water as they process. So using a system like that is going to waste a lot of water

Thanks for the excellent feedback everyone -- I'm still not sure which path to take but the info here is much more than I had before and gives some framework for making a decision.

I am initially tempted to just go with the truck approach and have the water cleaned using reverse osmosis service once/year, or when CH levels get too high, but we're a salt pool....and it appears I'd have to complete replace the salt in the pool after every cleaning which would also involve shutting down the SWG temporarily and then ensuring that after reactivation that the pool chemistry and SWG are returning to good states. Perhaps that is the right solution but not as simple as it first appears and will take a lot of salt.

Our pool is covered (automatic safety) so I wouldn't expect much need to top off daily using the auto fill, but yeah will still have some evaporation and splash out. I'll considering putting in a water softener if the pool builder says its OK, but its unclear how large of a unit we would need and it does seem that would take up some significant additional space and require its own maintenance. I'd probably set it on a low setting to ensure any changes take place over a long time...but the risk of a misconfiguration or lack of monitoring causing severe problems to an expensive pebble sheen/etc is also something to take into account, plus the up front cost and ongoing supplies.

If the trade offs are equal, it might make sense to just go with the RO approach, basically -- we'd shut down the pool for major maintenance for one week/year which is probably not that bad honestly. Plus, no additional plumbing or equipment space/general maintenance complications. I assume the RO truck guys would verify that the resulting calcium levels were just above 200. I might need to readd some other chemicals/borates/cya too, I guess...I can handle all that as long as we're not talking about a month to re-stabilize the pool chemistry.

Most RO services re-balance your levels when they are done.

A water softener will only add sodium or potassium (chloride is not added to the water), what is the builder's concern with either one of those?

JasonLion - The RO Service is sounding better and better.

I spoke to my builder today, he agreed the RO service would be an excellent idea. He also suggested I may also want to take a look at the mpulse 3000 (some customers had looked at it, but no one had actually used it yet)-
http://www.4deepblue.com/MPULSE_3000_s/26.htm

I looked at the site and there didn't see anyway for customers to post unedited feedback so no idea how effective, if at all, that it is. I didn't see any pricing on it either.

I think we'll go with the RO service.

According to SCP. the MSRP is almost $1500.

I can't find any references that suggest aragonite is more soluble or has less propensity to adhere to a surface than calcite.

Upon reading their "independent" test data, I find it interesting that they were able to filter out calcium.

I smell snake oil too.

Scott

I would not consider the MPULSE, their basic science is incorrect.

http://www.4deepblue.com/Product_Movie_s/33.htm
http://www.youtube.com/watch?v=M1y86qcvupc

We just installed a water softener on our pool autofill. We're on a well, and 3 years after building the pool I had to do essentially a complete water replacement, readjustment of water chemistry, along with bead blasting the scale off the tile---alot of work! Softener has dual resin tanks, so one tank regenerates while you draw from the other. Considering flow rates, I should never run out of soft water. Installer put in a hose bib, for if I get impatient waiting for the autofill to refill pool after a backwash of the sand filter. He also put in a ball valve so I can mix my well water with soft, once I get pool CH down to around 200 or so. I'll report back on how well it actually works, after a while...