Considering a salt system in Austin, Texas

Good to know. I’ve noticed the limestone builders block everyone uses on their houses flakes off during freezes so yes could just be the stone they use around here.

Flaking during freezing is typically called spalling. It is a result of water penetration, followed by a freeze. As you know, when water freezes to ice, it expands. It can exert tremendous pressure to do so, causing the rock to fracture. Same thing happens to concrete. One of the reasons people think salt pools are bad for decking is from experience with spalled concrete walkways caused by using salt in the winter to melt the ice. The water gets deeper into the concrete and freezes again causing the top layer of concrete to spall. You've probably seen this. People assume that the salt in a salt pool will cause that to happen. As others have pointed out, the 3000ppm of salt for a SWG is less than 1/2 the saltiness of a human tear. It isn't anything to worry about--it is far, far, far less concentrated than throwing rock salt on a driveway or walkway.

In Austin, you aren't subject to that much freezing weather anyway. Yes, you do have a lot more limestone there, since it is a cheap local material. Limestone has its own advantages / disadvantages. It will erode over time as it is rather soft, and can spall from freezing temps and water exposure.

The solution, whether we are talking about concrete, sandstone, or limestone, is to seal the surface and re-seal it about every 3 years. Or just live with it and accept the weathered appearance.

My pool deck is concrete with an aggregate finish. I will hopefully be replacing it soon. It's over 35 years old. It's hot. It's murder on the feet (rough). It is starting to lift and hairline crack in places due to our expansive clay soils causing continued movement. It's one of a handful of cantilevered decks in the D/FW area that *hasn't* cracked at the beam. It can probably go another 20 years, but for comfort and appearance, I want to replace it.

But over the past 18 years of exposure to a "salt pool" it has had no damage attributable to the salt.

Don't worry, be happy.

Even with salt cell prices being up, I think that long-term you will save money over chlorine (whether liquid or solid--gas is no longer an option in most places). With the plant fires that have removed a lot of chlorine tablet manufacturing capacity combined with the continued supply chain issues, tablet and granular prices have skyrocketed.

Take care of your cell (keep it clean, but don't clean it unnecessarily & never with too strong acid--keep the water balanced) & it will last probably around 5 years. The initial equipment outlay is steep, but worth it IMO. There are people who say there is no cost difference. I'd just like to do the following exercise, using current prices from everyone's favorite / most-hated pool store, Leslie's:
3" trichlor tabs: $200/35lbs sale for $170/35lbs = $4.85/lb at sale price ...these are going to cause issues later with constantly rising CYA...

Chlorinator:
Hayward AquaRite w/ T-15 cell: $1800 +400lbs (10 bags) salt at $6.50 ea = $1865
rated for 580lbs chlorine (trichlor pounds equivalent) for cell life

580lbs Trichlor tabs at the current sale price: $2813

That's a $948 savings over the life of the 1st cell.

Replacement T-15 cell: $900
...good for another 580lbs Cl.
$1900 savings from the second cell

OK, you'll have to add a few bags of $6.50 / bag salt each year. Still...I think you get the point.

frogkick said:

I do have a water sheer and if I remember right, we bumped it up a bit because that looks really sad when it's not at least at 2200. Although with the ScreenLogic, I would be able to trigger that combo of if the waterfall is running, go up to 2200, right?

Honestly, the speeds are just what the installers told me to set and I never questioned it. How would I go about figuring out a better speed for my pump? How would I know if I'm too high or too low so that I can dial in to the right speed for my pool?

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Do you have a controller, or are you just setting the speeds on the pump itself?

I would consider scheduling the time I want the waterfall effects and slow it down when nobody's going to be watching it.

If you have a way of measuring flow (I put a flow meter on my plumbing), then you can see what flowrate you are getting at different speeds and determine the best speed / time combination to get at least 1 (and up to 3) turnovers of water in your pool a day. You can build a schedule around that. With a SWG, it's nice to operate at a lower speed for a longer time for continued chlorine generation. A lot of people run a low speed 24/7 for that and pay less electricity cost than running 8 hrs at higher speed. With SWG, you have to run the pump fast enough to keep the flow switch closed, but that's not very fast. Once I get a variable-speed pump (after my 2-speed dies or when/if I do a pool remodel), I will be targeting something like a 24hr low-speed runtime. The lower speed and longer runtime also help:
- keeping the surface skimmed via the skimmers
- less stress on the equipment to run at lower rates; less startup / shutdown stress
This is what I use for a flowmeter: https://www.amazon.com/H2-Flow-Controls-Control-Complete/dp/B09KDS6CKJ
Only instead of the full unit, they have a retrofit for a Jandy check valve. I already had a Jandy check valve in the right place, so I just replaced the top & flapper with their retrofit unit & voila! I can see how much flow I'm getting.

frogkick said:

One said no problem at all to install, the other said they'd have to completely drain the pool to do it because otherwise the existing water in the pool can damage the new system. Um. What?

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Um. What? Did he ask you for test results? Have you been using dry acid?

frogkick said:

Anyone know whether I'll have to drain the pool?

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Probably not. Can you post some test results? Sulfates from the use of dry acid, high CYA, and high CH can create problems for SWGs.

frogkick said:

I honestly never asked if he was using dry acid or muriatic because I just assumed everyone used muriatic. I don't know how to test for sulfates. I have a TF-100.

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We don't test for sulfates. It's moot issue anyways.

frogkick said:

I am terrified to do a partial drain, which I suspect is what I'm going to be recommended. I've read about it here, but I still can't quite picture it and I'm convinced I'm going to do damage.

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This is not a moot issue. I have to say it though...you'll need to exchange about 50-60% of the pool volume to get CYA into range. Tablets (trichlor) are bad news.

Here's an article on draining...

Draining - Further Reading

Let us know if you need help.

Using a submersible pump is the best way. You should make your pool guy do it, then fire him.

You should be good to go after that. I'm curious how your CH level stays so low. Is your fill line connected to softened water?

frogkick said:

I wonder if I’m doing the test wrong then. It’s supposed to turn blue, but mine goes from red to clear. User error?

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Can you confirm you used a 10 mL sample, not a 25 mL?

Each drop counts at 25 ppm?

So, no softener, correct?

The blue is somewhat faint, but it is blue.

frogkick said:

Just redid the test and yes, all of that is correct. It was my math that was off. It turned pale blue at 20 drops this time, which is 500. Thoughts on that calcium level?

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It's ok for now, but when you drain for CYA, you CH will be in a better spot. Optimally, you want to get your CH as low as possible since it will continue to rise with evaporative top offs. Any chance your home has a water softener you can tap into? If so, you may never need to drain again.

With volume of water removed is equal to the decrease in CYA (50% drain=50% CYA reduction). With CH, we need to calculate the CH of fill water that goes back in.

Can you test the CH of your fill water?

Your fill water calcium level is lower than I expected. That's great news. When the time comes, exchange between 50 to 60% of the pool volume.

Following TFP recommendations, it's nearly impossible to properly manage a pool with a CYA level of 160. Target FC level is 18 ppm and minimum is 12 ppm. PH test results are not valid with FC levels above 10 ppm.

For now, keep managing the pool the best you can,, and we'll help you get set up after your water exchange.