Saturation Index (Langelier, etc.)

[waterbear]

As for your comment about the Taylor Watergram's very construction not allowing for accurate results, I don't understand that. It looks like I can easily get accuracy of 0.1 LSI. They make an assumption for CYA level since the watergram uses TA instead of Carbonate Alkalinity, but that's a minor error since a change of 30 in CYA results (at typical 7.5 pH) in about 10 TA change which results in a roughly 0.05 LSI change. Of course, Ben made the point about all the errors in the individual measurements introducing error in the LSI, but that's true whether the watergram is used or not.

Richard

The TA can be ajusted for CYA and that result used on the watergram so that point is moot.

[chem geek]

The TA can be ajusted for CYA and that result used on the watergram so that point is moot.

You are right. I forgot about that. It's been a while since I've used the watergram since I've got my spreadsheet instead. I took a quick look at it in responding to your post and saw the "Total Alkalinity" scale, but forgot they had a CYA adjustment in their instructions so that the watergram scale is really "Carbonate Alkalinity" -- too bad they didn't mark it that way to begin with.

By the way, I'm going on vacation later this week through the next and won't have Internet access so if you don't hear from me, that's why.

[medvampire]

Richard
First of all let me commend you on your calculations and models. I had though about doing something along the same lines but just don’t have the time. I do agree that looking at the models of what could be happening can be of great importance. I don’t want to discourage you in any way of seeking the truth behind what is occurring in our pools, after all science is about the truth. The only caution I have is due to assuming constants that cannot be assumed but that are very dynamic. I have followed your post with great interest and have learned from your models. The models you have presented here are very informative but in the end it’s a Schrödinger’s cat situation.
Steve

[chem geek]

Richard
First of all let me commend you on your calculations and models.

The models you have presented here are very informative but in the end it’s a Schrödinger’s cat situation.
Steve

Steve,

Well, I certainly hope that my looking at the pool and taking measurements is not causing a quantum state reduction that affects my results. Seriously, I thank you for the compliment and encouragement and I hope that if and when I stray too far to extending a model when it simply won't fit or sounding too pompous or absolute about a result, that you chime in with a word of reason and caution. I'll try to be more careful with my posts in the newbie sections since my attempts at brevity can sometimes lead to sounding more authoritative than is justified.

Richard

[waterbear]

Richard,
I think your theoretical discussions of pool chemistry are extremely important! They provide a good basic model that we can then apply to real world instances and in doing so discover what other factors are playing a role in the outcome.....keep up the good work!

[medvampire]

Richard
Well, I certainly hope that my looking at the pool and taking measurements is not causing a quantum state reduction that affects my results.

Richard
If I find a worm hole in my back yard its your fault.
Steve

[DaveD]

Saturation or scaling indices - puckorius, Ryzner or Langlier are used extensively in the water treatment industry to prevent scaling on heat exchangers (heaters) and we also use them on the industrial pad type humidifers (Munters). I am no expert on them though I do know that using them will prevent excessive scale (calcium) build up. While everyone dumps on pool stores that use them improperly, they can help in a situation where scaling is an issue. An example is my fathers hot tub and his unsoftened well water with a Calcium level of 1000 from the tap. He has scale rings foring in the fiberglass tub and is concerned about his heater scaling. So who knows how to use properly and can tell me the right combination of Alkalinity, pH, etc. to stop his scaling?