Chlorine test chemicals giving false results?

[pnovak]

I have been using my TF-100 test kit for about 4 yrs now and seemingly, everything has been fine.

I just treated my pool for pink algae using yellow-out (which I have used before w/no problems). I am completely done with the treatment and now normalizing my chemicals.

I did a chlorine test this morning, and put the R-0870 powder into my 10 ml pool water and swirled. It came out very light pink. I put in one drop of R-0871 and it cleared right up - so, I had almost no chlorine - I left things as they were (water in tube, test kit on the kitchen table) and got distracted for about 1 1/2 hours - ran to pool store for chlorine, put in 90oz for an 18k pool, goofed off.

When I came back to the kitchen, the water sample was pink again! I put in another 8 drops of R-0870 which left it clear. I decided to leave it and see what happened....pink again 10 minutes later! I ended up putting in a total of 13 drops of the R-0870. Has anyone seen this before??

What's up with the delayed effects???

 

[Isaac-1]

It is just the way the test works, you have 5 or so minutes from the time you start the test to get a valid reading

 

[Holydoc]

Pnovak,

In the section entitled "Pool School", there is an area called " Extended Test Kit Directions". This can be found with the link:

Pool School - FAS-DPD Chlorine Test

You will notice when looking at the "NOTES" section that bullet number 3 mentions this phenomenon. It is perfectly normal.

 

[domct203]

I have been using my TF-100 test kit for about 4 yrs now and seemingly, everything has been fine.

I just treated my pool for pink algae using yellow-out (which I have used before w/no problems). I am completely done with the treatment and now normalizing my chemicals.

I did a chlorine test this morning, and put the R-0870 powder into my 10 ml pool water and swirled. It came out very light pink. I put in one drop of R-0871 and it cleared right up - so, I had almost no chlorine - I left things as they were (water in tube, test kit on the kitchen table) and got distracted for about 1 1/2 hours - ran to pool store for chlorine, put in 90oz for an 18k pool, goofed off.

When I came back to the kitchen, the water sample was pink again! I put in another 8 drops of R-0870 which left it clear. I decided to leave it and see what happened....pink again 10 minutes later! I ended up putting in a total of 13 drops of the R-0870. Has anyone seen this before??

What's up with the delayed effects???

That is normal behavior. Once the pink has turned to clear the FC test is over, and if checking CC it should be done immediately.

If you put in the R-870 and the color is very light pink, you are safe to put in another scoop to make it a bit darker, it will not effect the result.