Saturation Index and vinyl pool ...

[swimlane]

Does this matter with a vinyl pool? All my levels are good but I have done nothing with calcium hardness as advised. The pool calc shows a -1.5 SI and I just want to make sure that I do not need to adjust other values to get SI right. I believe that I read that the more negative value is corrosive for other than vinyl pools and a more positive value is corrosive for all pools.

Mark

[swimlane]

I believe watermom answered my question about SI in another thread ... not to worry then.

BTW, I love the Taylor test kit ... like the chemistry set I never had as a kid! I even got a guy at work to look at buying one; told him to sign up for this site and follow the link.
One thing though - as accurate as all the measurements are, the "dipper" confuses me. There could be quite a variance between each dipper full, so does the amount actually matter to the outcome of the test or is it just matter that the water changes color? I believe I even saw someone post that they only used one dipper. Also, I am still getting the hang of it and think I went one drop past it turning clear once ... does that effect the CC test? I can see running out of DPD powder and CYA reagents first.

[waste]

Ignore the SI for a liner pool with little calcium, but DO keep the alk in range.

As long as the water turns pink when you add the powder, you've added enough and you're good for adding the 871. I'm not sure, but I always retest the cc if I accidentally added an extra drop of 871 before adding the 0003 (maybe I'm just being 'overcautious', but I test the water to "KNOW" what's going on).

[swimlane]

Thanks Ted!
My levels are now at
FC: 5
CC: 0
PH: 7.4
TA: 70
CH: 20
CYA: 30
Salt: 3200

I'm still learning what level is appropriate for the SWCG and how much pump time. Just tonight I decreased the SWCG % and setup the timer for 6 - 10 AM and 4 - 8 PM ... any suggestions are welcome. I will retest CYA this weekend and add more if reading still the same. I am trying to follow the levels suggested by waterbear in the SWCG tweaking post although I haven't attempted the borates to 50 ppm yet.

[CarlD]

You are FINE. But since you have an SWCG you should raise CYA levels to that recommended in the manual. Do not raise TA, and only raise CH if the manufacturer of the SWCG calls for it (Don't want to void the warranty). SWCGs seem to do better with lower TA levels and higher CYA levels.

Carl