You guys are gonna love this...

[duraleigh]

Greg,

It's not clear to me how water without calcium is harmful to my pump. I always thought the white spots that formed on metals immersed in water were calcium deposits.

How much calcium do I need for a "balanced calcium level"?

[gregugadawg]

On a vinyl pool you can keep it around the 150 range, inside of your pump there is a mechanical seal which keeps the water from hitting the back of the motor. With corrosive water this will rust causing water to eventually leak which also means water is getting in the shaft.

[mwsmith2]

I can understand how there is need for some calcium in the pool for the pump...i'm just not exactly sure how the liner needs it too.

Michael

[gregugadawg]

nah i wouldnt necessarily say the liner needs it, I am just in atlanta here and the ch out of the tap is 80 ppm, i tend to get it to about 250 in a gunite pool, 150 for vinyl and fiberglass and 150 for spas. I wouldn't say it affects the liner but I did look on some major manufacturers of liners and they said to keep it 100-200. I know most places in the country arent gonna be 50-80 out of the tap like we are here.

[mwsmith2]

I do remember now Ben saying at one time that certain liners require a small bit of calcium in the water. I also did do a bit of playing around with the langelier saturation index, and if you subscribe that it's correct, it's impossible to stay out of the corrosive range without any Ca in the water. It seems that 100 - 150 is the range that keeps the index happy. I haven't researched it really all that hard, but I think i'm going to hit up some mechanical and chemical engineers at work tomorrow and see what they have to say.

Michael

[CarlD]

Greg,
Please explain to me how water without calcium is corrosive, but water with calcium is not.

I understand how high salt levels can be corrosive, how non-neutral pH can be be corrosive and how too much chlorine can be corrosive.

I also understand how a leechable chemical that is present in one environment, like the calcium in concrete or plaster pools will be dissolved by water that lacks calcium. Therefore calcium in the water presents a saturation to prevent it dissolving from the concrete or plaster.

But please explain to me how the vinyl will be damaged by low calcium if the other chemicals in the water are balanced? Exactly what elements react with the vinyl and how does the calcium prevent it?

Oh, and I keep my water VERY light on calcium and have YET to require a pump seal.

Oh, and by the way, I'm moving this thread to the China Shop.

[PoolDoc]

On a vinyl pool you can keep it around the 150 range, inside of your pump there is a mechanical seal which keeps the water from hitting the back of the motor. With corrosive water this will rust causing water to eventually leak which also means water is getting in the shaft.

Unfortunately, till I get caught up on kits, I can't pursue this issue. I'll try to get back to it in a week or so.

Meanwhile, Greg, I'm going to have to disable your registration. I'd asked you to back off, and read some of the PoolSolutions stuff before posting. Now, I've got some complaints, and a quick check shows you posting stuff that I've identified for years as TEKTATs (Things Everybody Knows That Aren't True). You can debate me on those points, in this section, but you can't post those sorts of things till you've done the debate.

(For starters, Professor Langlier did NOT think his index was applicable to pools, AND the product engineer with Canadian General (one of the major mfgs of vinyl sheet for pools) had never seen any evidence to support the calcium in vinyl pools recommendations.)

Regarding calcium:

• Calcium is NOT necessary for vinyl pools;
• Lack of calcium does NOT cause stainless steel seals to rust,
• Nor, does the presence of calcium decrease the corrosivity of water under the conditions that exist in pools, outside of heaters.
• Calcium's presence INCREASES the likelihood of damage to copper heat exchangers;
• etc.

I've done this debate many times before, but unfortunately, those archives are gone. I'll resurrect some of those this coming winter, but probably not before. But, once I have time to deal with this, I'll re-enable your registration and email you to let you know I've done so, and then we can duke it out here.

For everyone else . . . here are some of the relevant PoolSolutions pages:

http://www.poolsolutions.com/tips/tip72.html

http://www.poolsolutions.com/gd/chem_never.html

http://www.poolsolutions.com/tips/tip03.html

Ben

[mwsmith2]

For starters, Professor Langlier did NOT think his index was applicable to pools

Absolutely spot on, as usual. The index (and I'm just repeating this for the folks who don't know) was developed to keep boilers from corroding/scaling. In other words, it needs heat for it to be applicable. I'd say though, if you have a vinyl pool AND you have a heater, you're going to have a calcium requirement...because then you have a "boiler" that you are dealing with.

Again, this is an assumption on my part, but it seems to make sense.

Michael

[Rangeball]

I think this better explains Greg's positions-

"Retail Pool Store Manager, Previously worked for a commercial pool service company for 6 years."

His sig line, which apparently is turned off but still in his profile