FC Testing of Cold Water (55o F)

[taekwondodo]

As the water has gotten colder around here, I've noticed something weird when I do a FC test - particularly in a pool with a higher FC level (5+)...

The sample doesn't go "pink" as fast, so I wait... then after I drop-test the water goes clear. Then, 30 seconds later, it is a light pink... again. Add a drop or two of test solution, goes clear right away and then (depending on FC), goes light pink again.

Anyone else seen this?

Thanks.

- Jeff

 

[duraleigh]

As chem geek has posted before, everything slows down at colder temps. (sugar dissolves more slowly in colder water than warm).

As for the return to pink after the solution has cleared, that is perfectly normal and occurs regardless of the temperature. Disregard it. Once you have cleared the solution (endpoint), the test is completed.

 

[Bama Rambler]

All I can do is agree with Daves post. I've seen it do the same thing on my tests. Now I pour out the sample as soon as I'm done. That way it doesn't bother me to look at it. :-D outta sight, outta mind!

 

[taekwondodo]

As chem geek has posted before, everything slows down at colder temps. (sugar dissolves more slowly in colder water than warm).

As for the return to pink after the solution has cleared, that is perfectly normal and occurs regardless of the temperature. Disregard it. Once you have cleared the solution (endpoint), the test is completed.

But I've never seen it return to pink when the water is warmer... and I test a LOT of water.

 

[PaulR]

Well, try some experiments. Get your sample, then cup your hands around it for a minute to warm it up some... then test. Then run a second test letting it sit for the same length of time without warming up. See what happens.

In my own pool, sometimes I get the late-stage pink and sometimes not. I haven't noticed any particular pattern to it (but then I haven't been looking for one).

Another thing to remember is that with water temps now very low (mine was 52F today) the FC is less critical than during the summer.
--paulr