Saturation Index

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nthoms

nthoms

0
Jul 13, 2012
45
Colchester, CT
Please take a look at my chart below ... I am concerned about the Saturation Index. What should I do to help bring the Saturation Index back in-line?

As always, your help is greatly appreciated :)

[attachment=0:uyl9fjna]PoolChemistry6.29.2013.jpg[/attachment:uyl9fjna]
 
Who cares? You have a vinyl pool. There's no danger of plaster etching.

If you're obsessive, run the pH in the upper half of the comfort zone 7.5>7.8 and it should be fine.

What's important is: How does the pool look? Clear? Sparkly? No dry skin? No frizzy hair? No burning eyes? That's what's important. Nobody outside this board gives a hoot whether your numbers are perfect, but they'll sure notice perfect water.
 
@Richard

I was concerned about the cement around my pool, fiberglass steps, and metal ladder ... when I saw that the saturation index indicated corrosive I got concerned.

My pool water looks good. I've suffered for so many years with bad water (cloudy, algae, iron stains) This is my first year doing all this "testing" and I'm still trying to understand what it all means.

Sorry :oops: ... I guess I truly don't really understand all this pool Chemistry stuff ... I'm still trying to learn :(

But thanks for your "candid" reply.
 
nthoms said:
I was concerned about the cement around my pool, fiberglass steps, and metal ladder ... when I saw that the saturation index indicated corrosive I got concerned.

My pool water looks good. I've suffered for so many years with bad water (cloudy, algae, iron stains) This is my first year doing all this "testing" and I'm still trying to understand what it all means.

Sorry :oops: ... I guess I truly don't really understand all this pool Chemistry stuff ... I'm still trying to learn :(

But thanks for your "candid" reply.
Click to expand...
Yeah, I should have put a smiley in there. :oops:
 
Richard320 said:
nthoms said:
I was concerned about the cement around my pool, fiberglass steps, and metal ladder ... when I saw that the saturation index indicated corrosive I got concerned.

My pool water looks good. I've suffered for so many years with bad water (cloudy, algae, iron stains) This is my first year doing all this "testing" and I'm still trying to understand what it all means.

Sorry :oops: ... I guess I truly don't really understand all this pool Chemistry stuff ... I'm still trying to learn :(

But thanks for your "candid" reply.
Click to expand...
Yeah, I should have put a smiley in there. :oops:
Click to expand...
So it's safe to say that I don't need to pay any attention to the SI?

Just keep plugging along keeping my numbers within range?
 
I don't really understand CSI but I did notice that your tests seem to be about a week apart. Do you test more often and this just doesn't show that? I would think that might be a tad long between tests? The risks of going for days on end with less than ideal numbers can be scary.... :shock:
 
The cement around the pool is not constantly immersed in water. It also gets rained on and the rain likely has a very negative saturation index due to near zero calcium hardness (CH). It will wear on the concrete, but not quickly. Low pH is much more detrimental as it accelerates the rate of dissolving, not just whether it can dissolve at all. If you are concerned about your concrete, I suggest you seal it. We have troweled concrete that we seal every year with Glaze 'N Seal Multi-Purpose Sealer. We seal because of weathering, not splash-out.
 

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chem geek said:
The cement around the pool is not constantly immersed in water. It also gets rained on and the rain likely has a very negative saturation index due to near zero calcium hardness (CH). It will wear on the concrete, but not quickly. Low pH is much more detrimental as it accelerates the rate of dissolving, not just whether it can dissolve at all. If you are concerned about your concrete, I suggest you seal it. We have troweled concrete that we seal every year with Glaze 'N Seal Multi-Purpose Sealer. We seal because of weathering, not splash-out.
Click to expand...

Wow, thank you for the information. It's exactly the comments I was looking for. I've become proficient at testing the water, but I'm still trying to learn what it all means and what the impact of each component is.

I've kept the PH low because it seems like when I raise the PH I start to get metal (iron) staining on my fiberglass steps. Any insights??? Or suggestions???
 
YippeeSkippy said:
I don't really understand CSI but I did notice that your tests seem to be about a week apart. Do you test more often and this just doesn't show that? I would think that might be a tad long between tests? The risks of going for days on end with less than ideal numbers can be scary.... :shock:
Click to expand...

I test with my kit every Saturday ... in between those tests I will test with strips (but I don't record those).
 
nthoms said:
I've kept the PH low because it seems like when I raise the PH I start to get metal (iron) staining on my fiberglass steps. Any insights??? Or suggestions???
Click to expand...
Your pH is usually around 7.4 which is fine and the lowest was 7.0. When I say low pH with regards to concrete, I'm talking about lower than that. I wouldn't worry about the splash-out. You can seal it for general weathering -- good sealants also protect the concrete somewhat from sunlight as well, but that mostly applies to colored concrete.

Do you use a metal sequestrant? If so, it needs to be added every week or two in a maintenance dose since chlorine will slowly break it down. If you aren't using a metal sequestrant and are just preventing the pH from getting too high, that's fine and up to you -- it's just a little risky if you lapse and the pH gets high.

Having some CH in the water, usually around 150 ppm or so, does seem to help against cobalt staining, but I'm not sure about iron staining. The good news is that iron stains are the easiest to remove -- a little ascorbic acid does the trick. You can learn more by reading the Pool School article Metals in the Water and Metal Stains.
 
nthoms,

In your sig you mention a salt water pool but does that include a SWCG? It is a little easier to maintain a clean cell if the CSI is slightly negative.
 
I try to keep mine between 0 and -0.5 but I have a plaster pool so I don't want to get the CSI too low. But in your case, I think the numbers are fine.
 
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