fill water TA 500!! Richard, Carl, Evan, Al help!!!

[induce]

update: fill water.
bypassed the softener.....
ph 7.0 off scale looks maybe like 6.8 or 6.9
fc 6.0
ta 390
ch 300
which is better???? i was hoping to use the softener to help catch any metals before they got to the pool.

on a good note, i should have "city water" here by July. so hopefully only the first fill and a few top-offs to battle.

[chem geek]

First, why is there Free Chlorine in your fill water -- 2 ppm after the water softener and 6 ppm before? It sounded like you are getting the water from a well, but is it from some other local source or are you chlorinating it?

Second, the difference in TA between your two measurements is completely explained by the difference in pH. A pH of 7.6 with a TA of 500 is identical to a pH of 6.87 with a TA of 390 in terms of having the same amount of total carbonate in the water. So in essence, your water softener is ONLY substituting the calcium (and magnesium) in the water with sodium and/or potassium. It isn't changing your carbonate.

I don't quite understand why your water softener has raised the pH of the water. Your pre-to-post numbers are consistent with having 7.3 pounds of caustic soda / lye / sodium hydroxide added per 10,000 gallons.

As for which is better, the decision should really be based solely on the difference in calcium hardness and other benefits such as removal of metals. If there are indeed metals in the water, then using the post-water-softener would be best. If not and if you have a plaster pool, then using the pre-water-softener will get you the CH you need without having to add any calcium chloride (for a vinyl pool you won't need as much calcium).

Either way, you are going to have a heck of a fun time getting your TA lowered. The good news is that aeration will rather quickly outgas carbon dioxide so it won't take long to get the TA down, though it will take a LOT of acid, about 93 cups of Muriatic Acid per 10,000 gallons (over an extended period of time while aerating and keeping the pH low around 7.0 until your TA reaches 100 and then continuing to aerate without adding acid to let the pH get up to 7.5).

Richard

[CarlD]

Do you also have an acid neutralizer? That is a common setup with well water to have have both the softener and the neutralizer--it's a second smaller tank. And, with well water's pH of less than 7.0, it's VERY likely, because otherwise, over time, the acidity will weaken the pipes in your house.

If so, that answers Chem_Geek's question right there.

Either way, unless you bring in other water, you wil have to do a lot of the T/A reduction. Be VERY careful not to add ANY calcium until T/A is in the proper 80-125 range for nomal pH or your water could go cloudy.

[induce]

thanks guys!!

richard, as you know, the softener does indeed add salt, and yes i am adding chlorine to the water via injector. the reason the 2nd sample is higher is that the softener has a weak (old) carbon filter inline.
So use the softened water, fix the pH, aerate, fix the pH, aerate and repeat until the TA is 80-90 and then let the pH come up (aerating) until 7.3-7.5 ?
thanks carl, but there is no acid tank used. there are holding tanks that allow the sulfur to precipate out by reaction with the chlorine. the tanks are flushed monthly (from the bottom to let the precip out).
This is a 22-25k salt ig vinyl pool.
you know, on my old pool, the pb used proteam supreme. I read evan's borate experiment, any update? I was thinking of using the borate again. thought's ?