Can FAS-DPD Test use dilution?

[cschnurr]

My neighbour has a pool algae and high stabilizer level.
I have done a partial drain and refill, and am doing SLAM and tesing regularly.

I have Taylor K2006C with FAS-DPD chlorine test which has a 1ppm resolution if I use 10mm vial.
I am concerned that in testing so often I may run of reagant. For my purpose, I don't need this level of resolution

I just want to make sure I dilute the sample with tap water by
1:1, 1 part sample:1 part tap water to get 2 ppm resolution.
1:2, 1 part sample:1 part tap water to get 3 ppm resolution.
1:3, 1 part sample:3 part tap water to get 4 ppm resolution
(I recognize that this ignores the minor effect of tap water chlorination.)

Thanks

 

[YippeeSkippy]

Just use 5 cc pool water so each drop equals 1. This is one way to save on reagents when running low.

 

[Donldson]

Tap water has between 1-3 ppm TC, so I wouldn't call it a minor effect. Also doing it this way will throw the accuracy out the door. At 10 ml (which gives you a 0.5 ppm resolution, not 1 ppm) it is about +/- a drop, so you'll be within 1 ppm. At 5 ml each drop is equal to 1 ppm, so you have an answer within about 2 ppm. Actually a bit more variable since that lower amount of water means minor differences in sample sizes are magnified. Overall though it's good enough for a SLAM but not for regular maintenance. Greater than that is unacceptable. Your 4 ppm resolution idea would introduce more than an 8 ppm margin of error, not even counting the error introduced with tap water chlorination. That's not a reasonable margin in any circumstance.

 

[cschnurr]

Thanks so much!