So what are these salts, and why are they evil?

[Richard320]

One serious question and some venting here.

Last week I went in to the national chain pool store to pick up some liquid Chlorine. The store manager tried to sell me Trichlor or something.
"A four pound box is much easier to handle than 30 pounds of jugs!"
"I already have too much Calcium."
"Oh, well, then, this other stuff doesn't have Calcium."
"It has cyanuric acid. I have too much of that, too."
"Well, when one gets too high, switch to the other. And when they both get too high, it's time to change water."
"But we're in drought conditions. Can't do it now."
"But the liquid stuff leaves all kinds of salts and dissolved solids!"

Today I was off. So I enjoyed my morning coffee and cigarettes testing the pool water. I added some acid and left the filter running. Plan to add more Chlorine this evening.

Late this afternoon, the pool service showed up. Not the owner, but his daughter. After our exchange, I am so looking forward to firing them in a couple weeks, once we're back from Europe. But I digress.

She said she tested the water and said it looks good. I imagine it would. My TF-100 vs her bottle of test strips. I told her I added some acid this morning. She said that must be why it was on the low end - she didn't need to add hardly any acid. (It was 7.4) Then she said, "The Chlorine looks good." Well, it isn't. It was at 12.0 at 7 AM, should be kept above 11 with the CYA level they left me with. And it was 3 PM when she tested. I'm sure it is off the scale of her test strip. Anyway, I mentioned that we'll be gone soon, and I'd like to leave some Chlorine out for her to add when she comes.

"Well, it's about time to put the floater back in."
"I took it out and have been adding liquid Chlorine." (I called and told her dad that months ago, I guess he never passed it along.)
"Liquid Chlorine leaves salts."
"The floater leaves too much cyanuric acid. I was up above 220 before I started pumping it out and let the rain dilute it."
"But the floater Chlorine is stabilized."

I didn't bother to tell her I don't want my Chlorine totally stable. I want it to be active! If I want it totally stable, I'd buy single pucks and leave them in the airtight wrapper!

Okay, vent over, back to the serious question to which I alluded earlier.

What are these salts in Sodium Hypochlorite, and why are they so evil?

 

[bk406]

Ha. It's just pure old salt, NaCl. Any form of sodium hypochlorite will leave salt. I think chemgeek has a thread on it somewhere. It's not much, really. Those presious pucks they love leave it too.

BTW, the coffee and cigs sound good. I quit 4 years ago. In the morning with coffee, i could still smoke one about a foot long

 

[JasonLion]

Enough trichlor to raise FC by 1 will raise the salt level by 0.8. Enough bleach to raise FC by 1 will raise the salt level by 1.6. So, yes using bleach will raise the salt level by more than trichlor will. On the other hand there is nothing wrong with a little salt in the pool, in fact it can make the water feel better. Neither trichlor or bleach will add enough salt to ever get you into the range of SWG salt levels. There is always some water replacement, and even 3 ppm of salt a day will take a really long time to get up into the thousands. In a typical pool that has been using bleach for years salt might get up to 1,200, though it can be higher or lower than that depending on the rate of water replacement.

 

[svenpup]

...Late this afternoon, the pool service showed up....

What!? You still have a pool service? I am shocked!

...I didn't bother to tell her I don't want my Chlorine totally stable. I want it to be active! If I want it totally stable, I'd buy single pucks and leave them in the airtight wrapper!...

In the wrapper...you're killing me :lol:



It is funny that half the people here use salt at 3000+ ppm for their SWCG and many more use salt at 2000+ ppm just because it make the water feel nicer and they are worried about a few (harmless) ppm while simultaneously unconcerned about huge amounts of CYA rendering your sanitizer useless and huge amounts of calcium causing scaling.

 

[tedinelkgrove]

I am a biologist, so do not look at my chemical explanation as the end all be all Regardless, here is why I believe you have salt generation from using NaCLO:

3 NaCLO decomposes to NaCLO3 + 2 NaCL. It also reacts with HCL (but not sure about all the other chemical influences in the pool): 2 HCL + NaCLO produce CL2, H2O, and NaCL.

 

[JasonLion]

tedinelkgrove, you have it kind of right, but not quite. You can find detailed chemistry information in this post. (Most people probably don't want to know.)

 

[chem geek]

It's just easier to remember that for ANY source of chlorine, when that chlorine gets used up it creates chloride salt. For every 10 ppm FC, 8 ppm salt will be created. The link that Jason shows describes that process.

For sodium hypochlorite and lithium hypochlorite, there is also additional salt added upon addition. This comes from the manufacturing process itself where chlorine gas is added to lye so for every 10 ppm FC added by these sources of chlorine they immediately add 8 ppm salt. The net result for chlorine addition and consumption/usage combined is somewhat over 16 ppm salt.

In an SWG pool, chloride salt is used to generate the chlorine itself so there is no net change in salt level from the chlorine creation and consumption combined.