CC and Shocking

[jrv331]

I know the general rule is to shock when the CC level is over .5, but with a level that low would you even notice a color change? Im using a Taylor kit and dont even think I'd see the change.
Thanks
John

[CarlD]

You are pretty close. The problem is if you run the 10ml test, you cannot tell if it's actually .5, or less. If you see NO pink tint at all, it's 0ppm. But if there's a hint of pink and one drop of reagent clears it, it could be anything from just over 0 to .5, but no more.

A lot of us have found it to be very difficult to get that last bit out--and swim anyway. It can mean something--I had a very tiny but persistent bit of algae inside my drop-in steps that seemed to not be reachable even when FC was 15! This year I'm trying something else that seems to work.

Remember, though, you CAN do the test with 25ml. Then each drop represents .2ppm, not .5ppm, so you can get a better feel if it's only 0 to .2ppm-if it's definitely less than .5 (.2 or .4ppm) then don't worry about it.

[jrv331]

Thanks for the response. How would I use the 25ml tube? How many drops of solution would I need to add?
Thanks
JOhn

[Dr. Spike]

Thanks for the response. How would I use the 25ml tube? How many drops of solution would I need to add?
Thanks
JOhn

John,

You will use the same amount of drops as indicated in the instructions, the only difference is that you will multiply the number of drops you counted by 0.2 instead of 0.5.

I hope that makes sense.

Edit: So, instead of 1 drop = 0.5, it will be 1 drop = 0.2

[jrv331]

I think Im missing somethig here. With my current kit I just fill the vial to the marked lin then add the drops as instructed then compare to the pink on the chart. It goes from 1-5. For the CC test I add 5 more drops of a different solution then compare to the previous color. Im missing the part about .02 and .05 for multiplying. There is no multiplying in my kit - ist just compare the color after CC drops are added.
Thanks
John

[waterbear]

I think Im missing somethig here. With my current kit I just fill the vial to the marked lin then add the drops as instructed then compare to the pink on the chart. It goes from 1-5. For the CC test I add 5 more drops of a different solution then compare to the previous color. Im missing the part about .02 and .05 for multiplying. There is no multiplying in my kit - ist just compare the color after CC drops are added.
Thanks
John You are using the Taylor K-2005 which is a DPD test. the others were talking about the K-2006 which is an FAS-DPD titration test. With your kit if you see the color darken when you add reagent 3 you have CC. this kit really won't measure less than about 1 ppm CC so anything less will be subjective. If the color stays exactly the same then assume there is no CC, if it gets darker then you might want to shock.

[jrv331]

I was starting to wonder if I was doing something wrong. Thanks for the clarification.
John

[Dr. Spike]

Sorry for the confusion. Yes, I was talking about the FAS-DPD kit.