In a nutshell: Why the alk lowering process works

[CarlD]

Edit: Carl is correct that there is no reason to worry about TA in a vinyl pool as long as your calcium levels are not too high. You might need to add acid more freqently if you are using bleach but there really aren't any other negatives. If the calcium levels are high then the combination of high TA and high calcium can lead to scaling or clouding of the water, especially if you let your pH get out of line and rise.

Evan's right. Of course, too-high calcium is a problem for ALL pools, not just vinyl. If your calcium hits, say 500ppm and your T/A is 180 or 200ppm, you will almost definitely get a milk-white cloud.

But too-low calcium is NOT an issue for vinyl. And when it's low, higher T/A levels are fine.

[waterbear]

But too-low calcium is NOT an issue for vinyl. And when it's low, higher T/A levels are fine.

One often overlooked reason for having calcium in a vinyl pool is to help prevent foaming. Soft water will have more of a tendency to foam than hard water. Personally, I think a calcium hardness of around 100-150 ppm would be more than enough. Might be in intersting experiment if anyone cares to do it! Other than that low calcium should not be an issue at all!

[CarlD]

One often overlooked reason for having calcium in a vinyl pool is to help prevent foaming. Soft water will have more of a tendency to foam than hard water. Personally, I think a calcium hardness of around 100-150 ppm would be more than enough. Might be in intersting experiment if anyone cares to do it! Other than that low calcium should not be an issue at all!

Well, my CH level is 50ppm this season, pretty low, but I haven't seen ANY evidence of foaming, ever. How low does it have to be before that can happen? Also, I'm a bear about keeping my chlorine levels stable, so that's probably preventing it as well.

[waterbear]

depends on a number of factors. Pools that develop a scum line tend to have more organics (from body oils, suntan lotion, etc.) and might have more of a tendency to foam in very soft water. Not really a major issue. Was just pointing out another reason to keep the water in the pool a bit 'hard'.

[CarlD]

depends on a number of factors. Pools that develop a scum line tend to have more organics (from body oils, suntan lotion, etc.) and might have more of a tendency to foam in very soft water. Not really a major issue. Was just pointing out another reason to keep the water in the pool a bit 'hard'.

Not to mention keeping your chlorine levels up, too! Chlorine metabolizes that stuff. Can't foam if it isn't there!