Mind Blown -- no need to keep adding salt?

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scrumpto

scrumpto

Member
Sep 25, 2018
13
Lincoln, CA
An idea hit me the other day -- where does all the sodium go in my saltwater pool when the chloride is used up? After a few minutes of searching, I stumble onto a forum that says essentially that it gets bound up and is converted back via the addition of acid.

Long story short -- according to the forum post, as I use a cartridge filter (so no backwashing) I don't need to continually add salt, I simply need to treat the pool with acid.

If so, holy cr@p -- I've been adding salt every summer for four years.

Can someone set me straight and advise me on this? I'm not a noob at all when it comes to pools but I never realized this about saltwater pools.
 
The chloride doesn't get used up. The SWG turns the chloride into chlorine. When the chlorine does it's job killing stuff or it gets hit by UV, it gets turned back into chloride. Then the cycle starts again. And again...

Via muriatic acid you add a bit more chloride, but not that much compared to what's already in.

The sodium just hangs around.

Edit:

From Salt - Further Reading:
Every gallon of muriatic acid (31.45%) adds ~36ppm of chloride ions to 10,000 gallons of pool water.

For your 30k gal pool that means 12ppm of chloride per gallon of MA.

A 20kg bag of salt raises your chloride level by 176ppm. That means 1 bag of salt is equivalent to about 15 gallons of MA in terms of chloride. Really depends on amount of water lost if salt level can be maintained with MA alone. I can't.

And just to clarify, the acid doesn't convert anything back, it just adds H+ (which lowers pH) and Cl- (chloride). "Conversions" happen as I described at the beginning of this post.
 
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You have to add salt to replace the salt that you lose when backwashing, draining water when too much rain, or via splash out when the kids are having too much fun.
 
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Okay, those are REALLY cool answers so thank you to everyone for responding. I have a cartridge filter so no backwashing. Water is very rarely spilled out of the pool. My auto-fill runs a lot but I've always figured it was due to evaporation as we live in a very hot place with zero shade. How would I check for a leak?

Thanks for the tips on testing salt -- I'll be doing that ASAP.
 
With an auto-leveler, you can be losing water without knowing it. Big rainfall raises the pool over the drain level, so the excess quietly drains off.

To boot, with at least some levelers, the drained water comes from a couple feet down where the salt is, while the fresh rain is floating on top.

Where I live in NC, I figure up to 30 percent of the pool gets exchanged this way every year. This explains all the salt drop.

Unfortunately the same thing happens if the auto-leveler valve sticks open. The leak is the same as rain.
 
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