Fc Test Results

[rckymtntim]

I just used my taylor test kit to test my FC. I added my 2 scoops of R-0870 and swirled to dissolve, the sample turned pink as usual. I added over 100 drops of R-0003 DPD reagent and the sample showed no signs of change. My last good reading was on 7/3/10 when FC was measured at 8.6 using the same test agents. Since that date I have added approximately 1.5 cups of Bleach (I'm using the dichlor bleach method)and we have not used the hot tub since 7/2/10. My CD is about 30%.

It seems that my R-0003 is bad but could it go bad that fast with a good reading on 7/3 and a bad reading on 7/11? I purchased them less than 9 months ago. Is there any other explanation for this?

Thanks for your input.

Tim

[chem geek]

Tim,

You don't add the R-0003 DPD Reagent #3 to titrate the sample. After adding the scoops of R-0870 DPD powder, you add the R-0871 FAS-DPD titrating reagent to count the drops for Free Chlorine (FC). It is only after the sample then goes from pink to clear that you then add 5 drops of R-0003 to see if it turns pink again and if it does, you then add more R-0871 to count the drops for Combined Chlorine (CC). The Taylor K-2006 instructions are here.

If you just wrote the wrong reagent number in your post and were actually using the R-0871 reagent for counting the drops, then you can see from this link that a compromised R-0871 reagent will become dark yellow instead of its normal clear if the reagent has gone bad (which is unlikely in such a short time unless the bottle was exposed to high temps or the cap was left off exposing the contents to air). If the drops from any reagent bottle are not well-formed large hanging drops and instead come out as small squirting drops, then you need to wipe the dropper tip with a damp cloth or tissue to remove static electricity.

Richard

[rckymtntim]

Thanks Richard, I must have put the 2 bottles back in the wrong spots after my last good test.

Now, can we delete this so I don't look like a complete idiot lol.