Alkalinity Zero

[sdaggie]

Thank you for responding. What I meant when I said that it I can't get the Alk to turn from green to red is that the Alk is still registering zero (the test did the same thing before I added the Sod Bicarb).

When you say the CYA is very high - my printout shows ideal is 30-200.

I use BioGuard Silk Tabs and Burn Out shock each week. I think there is stabilizer in the tabs? My Total Hardness is 276.

I don't want to drain my pool. We had to do that a few years ago and it is not good for the liner (left wrinkles).

Any other suggestions? Thanks so much!

[kelemvor]

When you test your alk, use the 10ml sample size instead of 25ml. The loss in precision will have no bearing on how you dose your pool. Also, using the smaller sample size means you save reagents and time by using less drops to achieve the color change.

[chem geek]

Testing for chlorine in a FAS-DPD test with a 10 ml sample size makes sense since 0.5 ppm resolution is usually sufficient compared to 0.2 ppm with a 25 ml sample size. Calcium Hardness (CH) is another test where one could use a 10 ml sample size for a 25 ppm resolution. However, for Total Alkalinity (TA), the resolution of 10 ppm with a 25 ml sample size is usually needed. For initial TA adjustments the smaller sample size may be OK, but when making final adjustments the 10 ppm resolution is preferable.