Low CSI target with high CH & high TA fill water? Realistic?

[Pegasus_RPG]

I live in a hot and hard water area of the country. Fill water is 275ppm CH, 7.4 pH, 160 ppm TA as tested from my aerated kitchen faucet (running really slowly to minimize aeration.) Since I now have an SWG (and a calcium ring on the spa tiles,) I'm trying to keep CSI slightly negative (by targeting 7.2 pH) which is proving difficult with pool water CH between 725-775ppm (I can't seem to avoid a fading endpoint no matter what I try) high water temps (wife likes it around 90 F) that high fill TA and the SWG's aeration.

Is there anything I can do or am I just resigned to having to add 1-2 quarts of acid every couple of days? (Which admittedly isn't bad unless I go out of town for a couple weeks.) I'm loathe to drain and refill from conservation and financial standpoints.

I do have a solar blanket I keep on to minimize evaporation until the water gets over 92 degrees and I have to let it evaporate overnight to cool down. (That cover has paid for itself in just a couple months!)

 

[mknauss]

I have the same fill water.

I add acid twice a week. I can keep my TA around 80/90 and the CSI is ok until CH hits 800 ppm. Then it is time to exchange the water to fresh and start over.
I am planning to add a water softener this fall just to supply my pool fill water. That will take care of the CH issue, but the TA and pH will still need to be controlled using acid.

 

[Pegasus_RPG]

I add acid twice a week. I can keep my TA around 80/90 and the CSI is ok until CH hits 800 ppm. Then it is time to exchange the water to fresh and start over.

Do you exchange the entire volume?? How much does that end up costing?
About how long can you go between exchanges?

I am planning to add a water softener this fall just to supply my pool fill water.

Won't that end up costing more as I understand they need to "regenerate" periodically which consumes a lot of water?

I'm seriously thinking about building a rain catchment...that should be low pH, zero CH, low TA I guess and free!

 

[mknauss]

I exchange the entire volume. My pool is 6000 gallons. Water is under $20. Salt and CYA add up to about $30. So pretty cheap to do the exchange.

Regeneration of the water softener uses about 20 gallons of water. It would only do that every 2000 gallons or so with the unit I am looking at. So the operating cost is nil. The cost to install will be ~$500. I would do it myself. It is not an economic venture, as I can exchange my pool many times for that cost. But the water with high CH is 'drying' to the skin and my wife does not like that.

Rain cachement would not work too well here. Most of your evaporation is May - Sept. We do not get much rain during that time frame.

 

[Jimbarstow]

I successfully kept my pool balanced with CH at 1200. Granted, I was adding acid a couple times a week to keep the CSI in the desired range. It was during a drought and I was loathe to do a drain/refill with 21,000 gal. Refill water from my well was 350 ppm Ca and there was no way I was going to tax my well by drawing 21,000 gal.

My solution was to find a pool reverse osmosis service. They run the pool water through a RO system and you end up with incredibly pure water. There is some waste water but it is nothing like a drain/refill. I’m in Northern Ca but I’m sure there is a RO service in Nevada. They are more common in areas were water is precious. For me it was 1/2 the cost of a drain/refill and you end up with better water.

 

[Pegasus_RPG]

Oh great idea, Jim! I didn't realize those services existed. I found one here. They charge $525 for up to 30Kgal and there's about a 14% loss to waste, so now I have to calculate what a straight exchange would cost me. (PSA: drain to your sewer cleanout and not the street! This way the water can be reclaimed by the sewage treatment facility.)

Thanks for the idea!

 

[Pegasus_RPG]

@mknauss I just talked to the RO company who said using soft water in the pool is a bad idea due to chance of plaster softening and easier staining. Of course they have incentive to scare me so I use their service repeatedly, but we already know here that we don't want ALL soft water in the pool!

 

[mknauss]

You still maintain a CH of 250+ in the pool water. So for instance, what I plan to do, is exchange my water to fresh and that will put my CH at around 300 ppm. Then switch to soft water. Test CH monthly. If it goes down, by pass the softener for a couple weeks. No big deal.

RO is worse! They remove all minerals. And then add calcium back in. And expensive. You can drain your pool and refill for under $150, including water, sump pump rental/purchase, and adding back in salt and CYA.

 

[Pegasus_RPG]

What about switching the fill to soft right away and only exchanging enough to lower CH to the desired point? That should save something like 40% of the water (and the salt & CYA with it,) right? Especially if we stop the pump for a few hours before starting the exchange to let the more dense calcium-heavy water settle to the bottom, and draw out from there, no?

 

[mknauss]

Sure, if your softener can keep up. It will have to regen a few times I would think Depends on the size of your softener.

 

[Pegasus_RPG]

My only conflict now is that my pool water is ~90 degrees and the fill water is at least 10-15 degrees colder...reading the Wiki article doesn't prioritize the drain-from-bottom vs top factors (temp differential, salt/high CH.)

 

[mknauss]

Your fill water is that cool? Ours is way warmer than the pool.

The high CH and salt over powers the temperature difference.

 

[Jimbarstow]

Pool reverse osmosis is different house plumbed RO. When we did it, we could stop the process at whatever chemistry we wanted. We choose to terminate at Ca in the low 200’s. It does remove salt and CYA. I viewed this as a chance to start de novo.

for those of us in the parched west, under new threat of drought, it behooves us to save water wherever possible