Quote Originally Posted by ezpool
...I dropped half a tab into a cup of water and let it sit. About 9 hour later I tested the water with my Taylor DPD test kit and got some really weird results:

- Added 5 drops of R-0001. No color change, none expected.
- Added 5 drops of R-0002. Each drop turned pink as soon as
it hit the water but then immediately faded to clear. After
swirling, the solution was still completely clear.
- Added 5 drops of R-0003. The entire solution turned a very
very dark murky brown.

There was definitely a smell of chlorine so I think the tabs must be somewhat effective but the above results have me scratching my head. Would this be expected if there was much more chlorine in the water that the test was meant to measure?? Or if the tabs are bad?
First of all, if you dropped a half a tab in a cup of water and let it dissolve, your FC would be a gazillion ppm (not really, but really really high) and your PH would be around 2. You are using DPD testing which is only good up to 10 ppm of FC if I'm not mistaken (FAS-DPD powder test to 50 ppm if memory serves me correct). So your results aren't any good I'm sorry to say. The combination of extra high FC, your testing method being out of range with the low PH is bleaching the pink right out.

I would continue to use them in the pool and post some numbers like Janet suggested. That way you are actually seeing what is happening in the proper volumes and PH range.

Dave